I want to delete the first character of a string, if the first character is a 0. The 0 can be there more than once.
Is there a simple function that checks the first character and deletes it if it is 0?
Right now, I'm trying it with the JS slice()
function but it is very awkward.
This question is related to
javascript
string
Very readable code is to use .substring()
with a start set to index of the second character (1) (first character has index 0). Second parameter of the .substring()
method is actually optional, so you don't even need to call .length()
...
str = str.substring(1);
...yes it is that simple...
As @Shaded suggested, just loop this while first character of your string is the "unwanted" character...
var yourString = "0000test";
var unwantedCharacter = "0";
//there is really no need for === check, since we use String's charAt()
while( yourString.charAt(0) == unwantedCharacter ) yourString = yourString.substring(1);
//yourString now contains "test"
.slice()
vs .substring()
vs .substr()
EDIT: substr() is not standardized and should not be used for new JS codes, you may be inclined to use it because of the naming similarity with other languages, e.g. PHP, but even in PHP you should probably use mb_substr()
to be safe in modern world :)
Quote from (and more on that in) What is the difference between String.slice and String.substring?
He also points out that if the parameters to slice are negative, they reference the string from the end. Substring and substr doesn´t.
var s = "0test";
if(s.substr(0,1) == "0") {
s = s.substr(1);
}
For all 0
s: http://jsfiddle.net/An4MY/
String.prototype.ltrim0 = function() {
return this.replace(/^[0]+/,"");
}
var s = "0000test".ltrim0();
From the Javascript implementation of trim() > that removes and leading or ending spaces from strings. Here is an altered implementation of the answer for this question.
var str = "0000one two three0000"; //TEST
str = str.replace(/^\s+|\s+$/g,'0'); //ANSWER
Original implementation for this on JS
string.trim():
if (!String.prototype.trim) {
String.prototype.trim = function() {
return this.replace(/^\s+|\s+$/g,'');
}
}
The easiest way to strip all leading 0
s is:
var s = "00test";
s = s.replace(/^0+/, "");
If just stripping a single leading 0
character, as the question implies, you could use
s = s.replace(/^0/, "");
String.prototype.trimStartWhile = function(predicate) {_x000D_
if (typeof predicate !== "function") {_x000D_
return this;_x000D_
}_x000D_
let len = this.length;_x000D_
if (len === 0) {_x000D_
return this;_x000D_
}_x000D_
let s = this, i = 0;_x000D_
while (i < len && predicate(s[i])) {_x000D_
i++;_x000D_
}_x000D_
return s.substr(i)_x000D_
}_x000D_
_x000D_
let str = "0000000000ABC",_x000D_
r = str.trimStartWhile(c => c === '0');_x000D_
_x000D_
console.log(r);
_x000D_
var test = '0test';
test = test.replace(/0(.*)/, '$1');
You can do it with substring method:
let a = "My test string";
a = a.substring(1);
console.log(a); // y test string
try
s.replace(/^0/,'')
console.log("0string =>", "0string".replace(/^0/,'') );_x000D_
console.log("00string =>", "00string".replace(/^0/,'') );_x000D_
console.log("string00 =>", "string00".replace(/^0/,'') );
_x000D_
Example: http://jsfiddle.net/kCpNQ/
var myString = "0String";
if( myString.charAt( 0 ) === '0' )
myString = myString.slice( 1 );
If there could be several 0
characters at the beginning, you can change the if()
to a while()
.
Example: http://jsfiddle.net/kCpNQ/1/
var myString = "0000String";
while( myString.charAt( 0 ) === '0' )
myString = myString.slice( 1 );
//---- remove first and last char of str
str = str.substring(1,((keyw.length)-1));
//---- remove only first char
str = str.substring(1,(keyw.length));
//---- remove only last char
str = str.substring(0,(keyw.length));
Here's one that doesn't assume the input is a string
, uses substring
, and comes with a couple of unit tests:
var cutOutZero = function(value) {
if (value.length && value.length > 0 && value[0] === '0') {
return value.substring(1);
}
return value;
};
Did you try the substring
function?
string = string.indexOf(0) == '0' ? string.substring(1) : string;
Here's a reference - https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/String/substring
And you can always do this for multiple 0s:
while(string.indexOf(0) == '0')
{
string = string.substring(1);
}
Another alternative to get the first character after deleting it:
// Example string
let string = 'Example';
// Getting the first character and updtated string
[character, string] = [string[0], string.substr(1)];
console.log(character);
// 'E'
console.log(string);
// 'xample'
Source: Stackoverflow.com