I'm trying to get a case-insensitive search with two strings in JavaScript working.
Normally it would be like this:
var string="Stackoverflow is the BEST";
var result= string.search(/best/i);
alert(result);
The /i flag would be for case-insensitive.
But I need to search for a second string; without the flag it works perfect:
var string="Stackoverflow is the BEST";
var searchstring="best";
var result= string.search(searchstring);
alert(result);
If I add the /i flag to the above example it would search for searchstring and not for what is in the variable "searchstring" (next example not working):
var string="Stackoverflow is the BEST";
var searchstring="best";
var result= string.search(/searchstring/i);
alert(result);
How can I achieve this?
This question is related to
javascript
search
string-comparison
case-insensitive
Replace
var result= string.search(/searchstring/i);
with
var result= string.search(new RegExp(searchstring, "i"));
ES6+:
let string="Stackoverflow is the BEST";
let searchstring="best";
let found = string.toLowerCase()
.includes(searchstring.toLowerCase());
includes() returns true if searchString appears at one or more positions or false otherwise.
Suppose we want to find the string variable needle in the string variable haystack. There are three gotchas:
string.toUpperCase and string.toLowerCase. Use a regular expression which ignores case instead. For example, var needleRegExp = new RegExp(needle, "i"); followed by needleRegExp.test(haystack).needle. Be careful that needle does not contain any regular expression special characters. Escape these using needle.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, "\\$&");.needle and haystack, just ignoring case, make sure to add "^" at the start and "$" at the end of your regular expression constructor.Taking points (1) and (2) into consideration, an example would be:
var haystack = "A. BAIL. Of. Hay.";
var needle = "bail.";
var needleRegExp = new RegExp(needle.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, "\\$&"), "i");
var result = needleRegExp.test(haystack);
alert(result);
You can make everything lowercase:
var string="Stackoverflow is the BEST";
var searchstring="best";
var result= (string.toLowerCase()).search((searchstring.toLowerCase()));
alert(result);
If you are concerned about the "unterminated character class" case, removing all non-alphanumeric chars would be helpful:
searchstring = searchstring.replace(/[^a-zA-Z 0-9]+/g,'');
If you're just searching for a string rather than a more complicated regular expression, you can use indexOf() - but remember to lowercase both strings first because indexOf() is case sensitive:
var string="Stackoverflow is the BEST";
var searchstring="best";
// lowercase both strings
var lcString=string.toLowerCase();
var lcSearchString=searchstring.toLowerCase();
var result = lcString.indexOf(lcSearchString)>=0;
alert(result);
Or in a single line:
var result = string.toLowerCase().indexOf(searchstring.toLowerCase())>=0;
If you're just searching for a string rather than a more complicated regular expression, you can use indexOf() - but remember to lowercase both strings first because indexOf() is case sensitive:
var string="Stackoverflow is the BEST";
var searchstring="best";
// lowercase both strings
var lcString=string.toLowerCase();
var lcSearchString=searchstring.toLowerCase();
var result = lcString.indexOf(lcSearchString)>=0;
alert(result);
Or in a single line:
var result = string.toLowerCase().indexOf(searchstring.toLowerCase())>=0;
ES6+:
let string="Stackoverflow is the BEST";
let searchstring="best";
let found = string.toLowerCase()
.includes(searchstring.toLowerCase());
includes() returns true if searchString appears at one or more positions or false otherwise.
Replace
var result= string.search(/searchstring/i);
with
var result= string.search(new RegExp(searchstring, "i"));
I do this often and use a simple 5 line prototype that accepts varargs. It is fast and works everywhere.
myString.containsIgnoreCase('red','orange','yellow')
/**_x000D_
* @param {...string} var_strings Strings to search for_x000D_
* @return {boolean} true if ANY of the arguments is contained in the string_x000D_
*/_x000D_
String.prototype.containsIgnoreCase = function(var_strings) {_x000D_
const thisLowerCase = this.toLowerCase()_x000D_
for (let i = 0; i < arguments.length; i++) {_x000D_
let needle = arguments[i]_x000D_
if (thisLowerCase.indexOf(needle.toLowerCase()) >= 0) {_x000D_
return true_x000D_
}_x000D_
}_x000D_
return false_x000D_
}_x000D_
_x000D_
/**_x000D_
* @param {...string} var_strings Strings to search for_x000D_
* @return {boolean} true if ALL of the arguments are contained in the string_x000D_
*/_x000D_
String.prototype.containsAllIgnoreCase = function(var_strings) {_x000D_
const thisLowerCase = this.toLowerCase()_x000D_
for (let i = 0; i < arguments.length; i++) {_x000D_
let needle = arguments[i]_x000D_
if (thisLowerCase.indexOf(needle.toLowerCase()) === -1) {_x000D_
return false_x000D_
}_x000D_
}_x000D_
return true_x000D_
}_x000D_
_x000D_
// Unit test_x000D_
_x000D_
let content = `_x000D_
FIRST SECOND_x000D_
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."_x000D_
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."_x000D_
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."_x000D_
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."_x000D_
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."_x000D_
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."_x000D_
FOO BAR_x000D_
`_x000D_
_x000D_
let data = [_x000D_
'foo',_x000D_
'Foo',_x000D_
'foobar',_x000D_
'barfoo',_x000D_
'first',_x000D_
'second'_x000D_
]_x000D_
_x000D_
let result_x000D_
data.forEach(item => {_x000D_
console.log('Searching for', item)_x000D_
result = content.containsIgnoreCase(item)_x000D_
console.log(result ? 'Found' : 'Not Found')_x000D_
})_x000D_
_x000D_
console.log('Searching for', 'x, y, foo')_x000D_
result = content.containsIgnoreCase('x', 'y', 'foo');_x000D_
console.log(result ? 'Found' : 'Not Found')_x000D_
_x000D_
console.log('Searching for all', 'foo, bar, foobar')_x000D_
result = content.containsAllIgnoreCase('foo', 'bar', 'foobar');_x000D_
console.log(result ? 'Found' : 'Not Found')_x000D_
_x000D_
console.log('Searching for all', 'foo, bar')_x000D_
result = content.containsAllIgnoreCase('foo', 'bar');_x000D_
console.log(result ? 'Found' : 'Not Found')I like @CHR15TO's answer, unlike other answers I've seen on other similar questions, that answer actually shows how to properly escape a user provided search string (rather than saying it would be necessary without showing how).
However, it's still quite clunky, and possibly relatively slower. So why not have a specific solution to what is likely a common requirement for coders? (And why not include it in the ES6 API BTW?)
My answer [https://stackoverflow.com/a/38290557/887092] on a similar question enables the following:
var haystack = 'A. BAIL. Of. Hay.';
var needle = 'bail.';
var index = haystack.naturalIndexOf(needle);
Replace
var result= string.search(/searchstring/i);
with
var result= string.search(new RegExp(searchstring, "i"));
You can make everything lowercase:
var string="Stackoverflow is the BEST";
var searchstring="best";
var result= (string.toLowerCase()).search((searchstring.toLowerCase()));
alert(result);
If you are concerned about the "unterminated character class" case, removing all non-alphanumeric chars would be helpful:
searchstring = searchstring.replace(/[^a-zA-Z 0-9]+/g,'');
If you're just searching for a string rather than a more complicated regular expression, you can use indexOf() - but remember to lowercase both strings first because indexOf() is case sensitive:
var string="Stackoverflow is the BEST";
var searchstring="best";
// lowercase both strings
var lcString=string.toLowerCase();
var lcSearchString=searchstring.toLowerCase();
var result = lcString.indexOf(lcSearchString)>=0;
alert(result);
Or in a single line:
var result = string.toLowerCase().indexOf(searchstring.toLowerCase())>=0;
I noticed that if the user enters a string of text but leaves the input without selecting any of the autocomplete options no value is set in the hidden input, even if the string coincides with one in the array. So, with help of the other answers I made this:
var $local_source = [{
value: 1,
label: "c++"
}, {
value: 2,
label: "java"
}, {
value: 3,
label: "php"
}, {
value: 4,
label: "coldfusion"
}, {
value: 5,
label: "javascript"
}, {
value: 6,
label: "asp"
}, {
value: 7,
label: "ruby"
}];
$('#search-fld').autocomplete({
source: $local_source,
select: function (event, ui) {
$("#search-fld").val(ui.item.label); // display the selected text
$("#search-fldID").val(ui.item.value); // save selected id to hidden input
return false;
},
change: function( event, ui ) {
var isInArray = false;
$local_source.forEach(function(element, index){
if ($("#search-fld").val().toUpperCase() == element.label.toUpperCase()) {
isInArray = true;
$("#search-fld").val(element.label); // display the selected text
$("#search-fldID").val(element.value); // save selected id to hidden input
console.log('inarray: '+isInArray+' label: '+element.label+' value: '+element.value);
};
});
if(!isInArray){
$("#search-fld").val(''); // display the selected text
$( "#search-fldID" ).val( ui.item? ui.item.value : 0 );
}
}
Replace
var result= string.search(/searchstring/i);
with
var result= string.search(new RegExp(searchstring, "i"));
I do this often and use a simple 5 line prototype that accepts varargs. It is fast and works everywhere.
myString.containsIgnoreCase('red','orange','yellow')
/**_x000D_
* @param {...string} var_strings Strings to search for_x000D_
* @return {boolean} true if ANY of the arguments is contained in the string_x000D_
*/_x000D_
String.prototype.containsIgnoreCase = function(var_strings) {_x000D_
const thisLowerCase = this.toLowerCase()_x000D_
for (let i = 0; i < arguments.length; i++) {_x000D_
let needle = arguments[i]_x000D_
if (thisLowerCase.indexOf(needle.toLowerCase()) >= 0) {_x000D_
return true_x000D_
}_x000D_
}_x000D_
return false_x000D_
}_x000D_
_x000D_
/**_x000D_
* @param {...string} var_strings Strings to search for_x000D_
* @return {boolean} true if ALL of the arguments are contained in the string_x000D_
*/_x000D_
String.prototype.containsAllIgnoreCase = function(var_strings) {_x000D_
const thisLowerCase = this.toLowerCase()_x000D_
for (let i = 0; i < arguments.length; i++) {_x000D_
let needle = arguments[i]_x000D_
if (thisLowerCase.indexOf(needle.toLowerCase()) === -1) {_x000D_
return false_x000D_
}_x000D_
}_x000D_
return true_x000D_
}_x000D_
_x000D_
// Unit test_x000D_
_x000D_
let content = `_x000D_
FIRST SECOND_x000D_
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."_x000D_
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."_x000D_
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."_x000D_
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."_x000D_
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."_x000D_
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."_x000D_
FOO BAR_x000D_
`_x000D_
_x000D_
let data = [_x000D_
'foo',_x000D_
'Foo',_x000D_
'foobar',_x000D_
'barfoo',_x000D_
'first',_x000D_
'second'_x000D_
]_x000D_
_x000D_
let result_x000D_
data.forEach(item => {_x000D_
console.log('Searching for', item)_x000D_
result = content.containsIgnoreCase(item)_x000D_
console.log(result ? 'Found' : 'Not Found')_x000D_
})_x000D_
_x000D_
console.log('Searching for', 'x, y, foo')_x000D_
result = content.containsIgnoreCase('x', 'y', 'foo');_x000D_
console.log(result ? 'Found' : 'Not Found')_x000D_
_x000D_
console.log('Searching for all', 'foo, bar, foobar')_x000D_
result = content.containsAllIgnoreCase('foo', 'bar', 'foobar');_x000D_
console.log(result ? 'Found' : 'Not Found')_x000D_
_x000D_
console.log('Searching for all', 'foo, bar')_x000D_
result = content.containsAllIgnoreCase('foo', 'bar');_x000D_
console.log(result ? 'Found' : 'Not Found')I noticed that if the user enters a string of text but leaves the input without selecting any of the autocomplete options no value is set in the hidden input, even if the string coincides with one in the array. So, with help of the other answers I made this:
var $local_source = [{
value: 1,
label: "c++"
}, {
value: 2,
label: "java"
}, {
value: 3,
label: "php"
}, {
value: 4,
label: "coldfusion"
}, {
value: 5,
label: "javascript"
}, {
value: 6,
label: "asp"
}, {
value: 7,
label: "ruby"
}];
$('#search-fld').autocomplete({
source: $local_source,
select: function (event, ui) {
$("#search-fld").val(ui.item.label); // display the selected text
$("#search-fldID").val(ui.item.value); // save selected id to hidden input
return false;
},
change: function( event, ui ) {
var isInArray = false;
$local_source.forEach(function(element, index){
if ($("#search-fld").val().toUpperCase() == element.label.toUpperCase()) {
isInArray = true;
$("#search-fld").val(element.label); // display the selected text
$("#search-fldID").val(element.value); // save selected id to hidden input
console.log('inarray: '+isInArray+' label: '+element.label+' value: '+element.value);
};
});
if(!isInArray){
$("#search-fld").val(''); // display the selected text
$( "#search-fldID" ).val( ui.item? ui.item.value : 0 );
}
}
There are two ways for case insensitive comparison:
Convert strings to upper case and then compare them using the strict operator (===). How strict operator treats operands read stuff at:
http://www.thesstech.com/javascript/relational-logical-operators
Pattern matching using string methods:
Use the "search" string method for case insensitive search. Read about search and other string methods at: http://www.thesstech.com/pattern-matching-using-string-methods
<!doctype html>
<html>
<head>
<script>
// 1st way
var a = "apple";
var b = "APPLE";
if (a.toUpperCase() === b.toUpperCase()) {
alert("equal");
}
//2nd way
var a = " Null and void";
document.write(a.search(/null/i));
</script>
</head>
</html>
I like @CHR15TO's answer, unlike other answers I've seen on other similar questions, that answer actually shows how to properly escape a user provided search string (rather than saying it would be necessary without showing how).
However, it's still quite clunky, and possibly relatively slower. So why not have a specific solution to what is likely a common requirement for coders? (And why not include it in the ES6 API BTW?)
My answer [https://stackoverflow.com/a/38290557/887092] on a similar question enables the following:
var haystack = 'A. BAIL. Of. Hay.';
var needle = 'bail.';
var index = haystack.naturalIndexOf(needle);
If you're just searching for a string rather than a more complicated regular expression, you can use indexOf() - but remember to lowercase both strings first because indexOf() is case sensitive:
var string="Stackoverflow is the BEST";
var searchstring="best";
// lowercase both strings
var lcString=string.toLowerCase();
var lcSearchString=searchstring.toLowerCase();
var result = lcString.indexOf(lcSearchString)>=0;
alert(result);
Or in a single line:
var result = string.toLowerCase().indexOf(searchstring.toLowerCase())>=0;
Suppose we want to find the string variable needle in the string variable haystack. There are three gotchas:
string.toUpperCase and string.toLowerCase. Use a regular expression which ignores case instead. For example, var needleRegExp = new RegExp(needle, "i"); followed by needleRegExp.test(haystack).needle. Be careful that needle does not contain any regular expression special characters. Escape these using needle.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, "\\$&");.needle and haystack, just ignoring case, make sure to add "^" at the start and "$" at the end of your regular expression constructor.Taking points (1) and (2) into consideration, an example would be:
var haystack = "A. BAIL. Of. Hay.";
var needle = "bail.";
var needleRegExp = new RegExp(needle.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, "\\$&"), "i");
var result = needleRegExp.test(haystack);
alert(result);
Source: Stackoverflow.com