How do you convert a string to a character array in JavaScript?
I'm thinking getting a string like "Hello world!"
to the array['H','e','l','l','o',' ','w','o','r','l','d','!']
Note: This is not unicode compliant.
"IπU".split('')
results in the 4 character array["I", "οΏ½", "οΏ½", "u"]
which can lead to dangerous bugs. See answers below for safe alternatives.
Just split it by an empty string.
var output = "Hello world!".split('');
console.log(output);
See the String.prototype.split()
MDN docs.
As hippietrail suggests, meder's answer can break surrogate pairs and misinterpret βcharacters.β For example:
// DO NOT USE THIS!
const a = 'ππππ'.split('');
console.log(a);
// Output: ["οΏ½","οΏ½","οΏ½","οΏ½","οΏ½","οΏ½","οΏ½","οΏ½"]
I suggest using one of the following ES2015 features to correctly handle these character sequences.
const a = [...'ππππ'];
console.log(a);
const a = Array.from('ππππ');
console.log(a);
u
flagconst a = 'ππππ'.split(/(?=[\s\S])/u);
console.log(a);
Use /(?=[\s\S])/u
instead of /(?=.)/u
because .
does not match
newlines. If you are still in ES5.1 era (or if your browser doesn't
handle this regex correctly - like Edge), you can use the following alternative
(transpiled by Babel). Note, that Babel tries to also handle unmatched
surrogates correctly. However, this doesn't seem to work for unmatched low
surrogates.
const a = 'ππππ'.split(/(?=(?:[\0-\uD7FF\uE000-\uFFFF]|[\uD800-\uDBFF][\uDC00-\uDFFF]|[\uD800-\uDBFF](?![\uDC00-\uDFFF])|(?:[^\uD800-\uDBFF]|^)[\uDC00-\uDFFF]))/);
console.log(a);
const s = 'ππππ';
const a = [];
for (const s2 of s) {
a.push(s2);
}
console.log(a);
The spread
Syntax
You can use the spread syntax, an Array Initializer introduced in ECMAScript 2015 (ES6) standard:
var arr = [...str];
Examples
function a() {
return arguments;
}
var str = 'Hello World';
var arr1 = [...str],
arr2 = [...'Hello World'],
arr3 = new Array(...str),
arr4 = a(...str);
console.log(arr1, arr2, arr3, arr4);
The first three result in:
["H", "e", "l", "l", "o", " ", "W", "o", "r", "l", "d"]
The last one results in
{0: "H", 1: "e", 2: "l", 3: "l", 4: "o", 5: " ", 6: "W", 7: "o", 8: "r", 9: "l", 10: "d"}
Browser Support
Check the ECMAScript ES6 compatibility table.
Further reading
spread
is also referenced as "splat
" (e.g. in PHP or Ruby or as "scatter
" (e.g. in Python).
Demo
This is an old question but I came across another solution not yet listed.
You can use the Object.assign function to get the desired output:
var output = Object.assign([], "Hello, world!");
console.log(output);
// [ 'H', 'e', 'l', 'l', 'o', ',', ' ', 'w', 'o', 'r', 'l', 'd', '!' ]
Not necessarily right or wrong, just another option.
There are (at least) three different things you might conceive of as a "character", and consequently, three different categories of approach you might want to use.
JavaScript strings were originally invented as sequences of UTF-16 code units, back at a point in history when there was a one-to-one relationship between UTF-16 code units and Unicode code points. The .length
property of a string measures its length in UTF-16 code units, and when you do someString[i]
you get the ith UTF-16 code unit of someString
.
Consequently, you can get an array of UTF-16 code units from a string by using a C-style for-loop with an index variable...
const yourString = 'Hello, World!';
const charArray = [];
for (let i=0; i<=yourString.length; i++) {
charArray.push(yourString[i]);
}
console.log(charArray);
There are also various short ways to achieve the same thing, like using .split()
with the empty string as a separator:
const charArray = 'Hello, World!'.split('');
console.log(charArray);
However, if your string contains code points that are made up of multiple UTF-16 code units, this will split them into individual code units, which may not be what you want. For instance, the string 'ππππ'
is made up of four unicode code points (code points 0x1D7D8 through 0x1D7DB) which, in UTF-16, are each made up of two UTF-16 code units. If we split that string using the methods above, we'll get an array of eight code units:
const yourString = 'ππππ';
console.log('First code unit:', yourString[0]);
const charArray = yourString.split('');
console.log('charArray:', charArray);
So, perhaps we want to instead split our string into Unicode Code Points! That's been possible since ECMAScript 2015 added the concept of an iterable to the language. Strings are now iterables, and when you iterate over them (e.g. with a for...of
loop), you get Unicode code points, not UTF-16 code units:
const yourString = 'ππππ';
const charArray = [];
for (const char of yourString) {
charArray.push(char);
}
console.log(charArray);
We can shorten this using Array.from
, which iterates over the iterable it's passed implicitly:
const yourString = 'ππππ';
const charArray = Array.from(yourString);
console.log(charArray);
However, unicode code points are not the largest possible thing that could possibly be considered a "character" either. Some examples of things that could reasonably be considered a single "character" but be made up of multiple code points include:
We can see below that if we try to convert a string with such characters into an array via the iteration mechanism above, the characters end up broken up in the resulting array. (In case any of the characters don't render on your system, yourString
below consists of a capital A with an acute accent, followed by the flag of the United Kingdom, followed by a black woman.)
const yourString = 'AΜπ¬π§π©πΏ';
const charArray = Array.from(yourString);
console.log(charArray);
If we want to keep each of these as a single item in our final array, then we need an array of graphemes, not code points.
JavaScript has no built-in support for this - at least not yet. So we need a library that understands and implements the Unicode rules for what combination of code points constitute a grapheme. Fortunately, one exists: orling's grapheme-splitter. You'll want to install it with npm or, if you're not using npm, download the index.js file and serve it with a <script>
tag. For this demo, I'll load it from jsDelivr.
grapheme-splitter gives us a GraphemeSplitter
class with three methods: splitGraphemes
, iterateGraphemes
, and countGraphemes
. Naturally, we want splitGraphemes
:
const splitter = new GraphemeSplitter();
const yourString = 'AΜπ¬π§π©πΏ';
const charArray = splitter.splitGraphemes(yourString);
console.log(charArray);
<script src="https://cdn.jsdelivr.net/npm/[email protected]/index.js"></script>
And there we are - an array of three graphemes, which is probably what you wanted.
You can iterate over the length of the string and push the character at each position:
const str = 'Hello World';
const stringToArray = (text) => {
var chars = [];
for (var i = 0; i < text.length; i++) {
chars.push(text[i]);
}
return chars
}
console.log(stringToArray(str))
Array.prototype.slice will do the work as well.
const result = Array.prototype.slice.call("Hello world!");
console.log(result);