[javascript] How do I split a string into an array of characters?

var s = "overpopulation";
var ar = [];
ar = s.split();
alert(ar);

I want to string.split a word into array of characters.

The above code doesn't seem to work - it returns "overpopulation" as Object..

How do i split it into array of characters, if original string doesn't contain commas and whitespace?

You can use the regular expression /(?!$)/:

"overpopulation".split(/(?!$)/)

The negative look-ahead assertion (?!$) will match right in front of every character.

A string in Javascript is already a character array.

You can simply access any character in the array as you would any other array.

var s = "overpopulation";
alert(s[0]) // alerts o.

UPDATE

As is pointed out in the comments below, the above method for accessing a character in a string is part of ECMAScript 5 which certain browsers may not conform to.

An alternative method you can use is charAt(index).

var s = "overpopulation";
    alert(s.charAt(0)) // alerts o.

It's as simple as:

s.split("");

The delimiter is an empty string, hence it will break up between each single character.

Old question but I should warn:

Do NOT use .split('')

You'll get weird results with non-BMP (non-Basic-Multilingual-Plane) character sets.

Reason is that methods like .split() and .charCodeAt() only respect the characters with a code point below 65536; bec. higher code points are represented by a pair of (lower valued) "surrogate" pseudo-characters.

''.length     // —> 6
''.split('')  // —> ["?", "?", "?", "?", "?", "?"]

''.length      // —> 2
''.split('')   // —> ["?", "?"]

Use ES2015 (ES6) features where possible:

Using the spread operator:

let arr = [...str];

Or Array.from

let arr = Array.from(str);

Or split with the new u RegExp flag:

let arr = str.split(/(?!$)/u);

Examples:

[...'']        // —> ["", "", ""]
[...'']     // —> ["", "", ""]

For ES5, options are limited:

I came up with this function that internally uses MDN example to get the correct code point of each character.

function stringToArray() {
  var i = 0,
    arr = [],
    codePoint;
  while (!isNaN(codePoint = knownCharCodeAt(str, i))) {
    arr.push(String.fromCodePoint(codePoint));
    i++;
  }
  return arr;
}

This requires knownCharCodeAt() function and for some browsers; a String.fromCodePoint() polyfill.

if (!String.fromCodePoint) {
// ES6 Unicode Shims 0.1 , © 2012 Steven Levithan , MIT License
    String.fromCodePoint = function fromCodePoint () {
        var chars = [], point, offset, units, i;
        for (i = 0; i < arguments.length; ++i) {
            point = arguments[i];
            offset = point - 0x10000;
            units = point > 0xFFFF ? [0xD800 + (offset >> 10), 0xDC00 + (offset & 0x3FF)] : [point];
            chars.push(String.fromCharCode.apply(null, units));
        }
        return chars.join("");
    }
}

Examples:

stringToArray('')     // —> ["", "", ""]
stringToArray('')  // —> ["", "", ""]

Note: str[index] (ES5) and str.charAt(index) will also return weird results with non-BMP charsets. e.g. ''.charAt(0) returns "?".

UPDATE: Read this nice article about JS and unicode.

.split('') would split emojis in half.

Onur's solutions and the regex's proposed work for some emojis, but can't handle more complex languages or combined emojis. Consider this emoji being ruined:

[..."??"] // returns ["", "?", "?", ""]  instead of ["??"]

Also consider this Hindi text "????????" which is split like this:

[..."????????"]  // returns   ["?", "?", "?", "?", "?", "?", "?", "?"]

but should in fact be split like this:

["?","??","??","??","?"]

because some of the characters are combining marks (think diacritics/accents in European languages).

You can use the grapheme-splitter library for this:

https://github.com/orling/grapheme-splitter

It does proper standards-based letter split in all the hundreds of exotic edge-cases - yes, there are that many.

The split() method in javascript accepts two parameters: a separator and a limit. The separator specifies the character to use for splitting the string. If you don't specify a separator, the entire string is returned, non-separated. But, if you specify the empty string as a separator, the string is split between each character.

Therefore:

s.split('')

will have the effect you seek.

More information here

To support emojis use this

('Dragon ').split(/(?!$)/u);

=> ['D', 'r', 'a', 'g', 'o', 'n', ' ', '']