How can I process each letter of text using Javascript?
JavascriptStringJavascript Problem Overview
I would like to alert each letter of a string, but I am unsure how to do this.
So, if I have:
var str = 'This is my string';
I would like to be able to separately alert T
, h
, i
, s
, etc. This is just the beginning of an idea that I am working on, but I need to know how to process each letter separately.
I was thinking I might need to use the split function after testing what the length of the string is.
How can I do this?
Javascript Solutions
Solution 1 - Javascript
If the order of alerts matters, use this:
for (var i = 0; i < str.length; i++) {
alert(str.charAt(i));
}
Or this: (see also this answer)
for (var i = 0; i < str.length; i++) {
alert(str[i]);
}
If the order of alerts doesn't matter, use this:
var i = str.length;
while (i--) {
alert(str.charAt(i));
}
Or this: (see also this answer)
var i = str.length;
while (i--) {
alert(str[i]);
}
var str = 'This is my string';
function matters() {
for (var i = 0; i < str.length; i++) {
alert(str.charAt(i));
}
}
function dontmatter() {
var i = str.length;
while (i--) {
alert(str.charAt(i));
}
}
<p>If the order of alerts matters, use <a href="#" onclick="matters()">this</a>.</p>
<p>If the order of alerts doesn't matter, use <a href="#" onclick="dontmatter()">this</a>.</p>
Solution 2 - Javascript
It's probably more than solved. Just want to contribute with another simple solution:
var text = 'uololooo';
// With ES6
[...text].forEach(c => console.log(c))
// With the `of` operator
for (const c of text) {
console.log(c)
}
// With ES5
for (var x = 0, c=''; c = text.charAt(x); x++) {
console.log(c);
}
// ES5 without the for loop:
text.split('').forEach(function(c) {
console.log(c);
});
Solution 3 - Javascript
How to process each letter of text (with benchmarks)
https://jsperf.com/str-for-in-of-foreach-map-2</s>
for
Classic and by far the one with the most performance. You should go with this one if you are planning to use it in a performance critical algorithm, or that it requires the maximum compatibility with browser versions.
for (var i = 0; i < str.length; i++) {
console.info(str[i]);
}
for...of
for...of is the new ES6 for iterator. Supported by most modern browsers. It is visually more appealing and is less prone to typing mistakes. If you are going for this one in a production application, you should be probably using a transpiler like Babel.
let result = '';
for (let letter of str) {
result += letter;
}
forEach
Functional approach. Airbnb approved. The biggest downside of doing it this way is the split()
, that creates a new array to store each individual letter of the string.
> Why? This enforces our immutable rule. Dealing with pure functions > that return values is easier to reason about than side effects.
// ES6 version.
let result = '';
str.split('').forEach(letter => {
result += letter;
});
or
var result = '';
str.split('').forEach(function(letter) {
result += letter;
});
The following are the ones I dislike.
for...in
Unlike for...of, you get the letter index instead of the letter. It performs pretty badly.
var result = '';
for (var letterIndex in str) {
result += str[letterIndex];
}
map
Function approach, which is good. However, map isn't meant to be used for that. It should be used when needing to change the values inside an array, which is not the case.
// ES6 version.
var result = '';
str.split('').map(letter => {
result += letter;
});
or
let result = '';
str.split('').map(function(letter) {
result += letter;
});
Solution 4 - Javascript
One possible solution in pure javascript:
for (var x = 0; x < str.length; x++)
{
var c = str.charAt(x);
alert(c);
}
Solution 5 - Javascript
Most if not all of the answers here are wrong because they will break whenever there is a character in the string outside the Unicode BMP (Basic Multilingual Plane). That means all Emoji will be broken.
JavaScript uses UTF-16 Unicode for all strings. In UTF-16, characters beyond the BMP are made out of two parts, called a "Surrogate Pair" and most of the answers here will process each part of such pairs individually instead of as a single character.
One way in modern JavaScript since at least 2016 is to use the new String iterator. Here's the example (almost) straight out of MDN:
var string = 'A\uD835\uDC68B\uD835\uDC69C\uD835\uDC6A';
for (var v of string) {
alert(v);
}
// "A"
// "\uD835\uDC68"
// "B"
// "\uD835\uDC69"
// "C"
// "\uD835\uDC6A"
Solution 6 - Javascript
You can try this
var arrValues = 'This is my string'.split('');
// Loop over each value in the array.
$.each(arrValues, function (intIndex, objValue) {
alert(objValue);
})
Solution 7 - Javascript
New JS allows this:
const str = 'This is my string';
Array.from(str).forEach(alert);
Solution 8 - Javascript
One more solution...
var strg= 'This is my string';
for(indx in strg){
alert(strg[indx]);
}
Solution 9 - Javascript
It is better to use the for...of statement, if the string contains unicode characters, because of the different byte size.
for(var c of "tree ζ¨") { console.log(c); }
//"πA".length === 3
Solution 10 - Javascript
If you want to do a transformation on the text on a character level, and get the transformed text back at the end, you would do something like this:
var value = "alma";
var new_value = [...value].map((x) => x+"E").join("")
So the steps:
- Split the string into an array (list) of characters
- Map each character via a functor
- Join the resulting array of chars together into the resulting string
NOTE: If you need performance, there are probably better, more optimized solutions for this. I posted this one as a clean codestyle approach.
Solution 11 - Javascript
short answer: Array.from(string)
will give you what you probably want and then you can iterate on it or whatever since it's just an array.
ok let's try it with this string: abc|β«οΈ\nβͺοΈ|π¨βπ©βπ§βπ§
.
codepoints are:
97
98
99
124
9899, 65039
10
9898, 65039
124
128104, 8205, 128105, 8205, 128103, 8205, 128103
so some characters have one codepoint (byte) and some have two or more, and a newline added for extra testing.
so after testing there are two ways:
- byte per byte (codepoint per codepoint)
- character groups (but not the whole family emoji)
string = "abc|β«οΈ\nβͺοΈ|π¨βπ©βπ§βπ§"
console.log({ 'string': string }) // abc|β«οΈ\nβͺοΈ|π¨βπ©βπ§βπ§
console.log({ 'string.length': string.length }) // 21
for (let i = 0; i < string.length; i += 1) {
console.log({ 'string[i]': string[i] }) // byte per byte
console.log({ 'string.charAt(i)': string.charAt(i) }) // byte per byte
}
for (let char of string) {
console.log({ 'for char of string': char }) // character groups
}
for (let char in string) {
console.log({ 'for char in string': char }) // index of byte per byte
}
string.replace(/./g, (char) => {
console.log({ 'string.replace(/./g, ...)': char }) // byte per byte
});
string.replace(/[\S\s]/g, (char) => {
console.log({ 'string.replace(/[\S\s]/g, ...)': char }) // byte per byte
});
[...string].forEach((char) => {
console.log({ "[...string].forEach": char }) // character groups
})
string.split('').forEach((char) => {
console.log({ "string.split('').forEach": char }) // byte per byte
})
Array.from(string).forEach((char) => {
console.log({ "Array.from(string).forEach": char }) // character groups
})
Array.prototype.map.call(string, (char) => {
console.log({ "Array.prototype.map.call(string, ...)": char }) // byte per byte
})
var regexp = /(?:[\0-\uD7FF\uE000-\uFFFF]|[\uD800-\uDBFF][\uDC00-\uDFFF]|[\uD800-\uDBFF](?![\uDC00-\uDFFF])|(?:[^\uD800-\uDBFF]|^)[\uDC00-\uDFFF])/g
string.replace(regexp, (char) => {
console.log({ 'str.replace(regexp, ...)': char }) // character groups
});
Solution 12 - Javascript
When I need to write short code or a one-liner, I use this "hack":
'Hello World'.replace(/./g, function (char) {
alert(char);
return char; // this is optional
});
This won't count newlines so that can be a good thing or a bad thing. If you which to include newlines, replace: /./
with /[\S\s]/
. The other one-liners you may see probably use .split()
which has many problems
Solution 13 - Javascript
You can now use in keyword.
var s = 'Alien';
for (var c in s) alert(s[c]);
Solution 14 - Javascript
You can now iterate over individual Unicode code points contained in a String by using String.prototype[@@iterator]
, which returns a value of well known Symbol type Symbol.iterator
- the default iterator for array-like Objects (String
in this case).
Example code:
const str = 'The quick red π¦ jumped over the lazy πΆ! ε€ͺζ£δΊοΌ';
let iterator = str[Symbol.iterator]();
let theChar = iterator.next();
while(!theChar.done) {
console.log(theChar.value);
theChar = iterator.next();
}
// logs every unicode character as expected into the console.
This works with Unicode characters such as emoji or non-roman characters that would trip up legacy constructs.
Reference: [MDN Link to String.prototype@@iterator]1.
Solution 15 - Javascript
You can simply iterate it as in an array:
for(var i in txt){
console.log(txt[i]);
}
Solution 16 - Javascript
In ES6 / ES2015, you can iterate over an string with iterators
,as you can see in
var str = 'Hello';
var it = str[Symbol.iterator]();
for (let v of it) {
console.log(v)
}
// "H"
// "e"
// "l"
// "l"
// "o"
It is a declarative style. What is the advantage? You do not have to concern about how to access each element of the string.
Solution 17 - Javascript
You can get an array of the individual characters like so
var test = "test string",
characters = test.split('');
and then loop using regular Javascript, or else you can iterate over the string's characters using jQuery by
var test = "test string";
$(test.split('')).each(function (index,character) {
alert(character);
});
Solution 18 - Javascript
you can convert this string into an array of chars using split()
, then iterate through it.
const str = "javascript";
const strArray = str.split('');
strArray.map(s => console.log(s));
Solution 19 - Javascript
// There are multiple ways but I find this easiest.
let str = 'This is my string';
for(let character of str)
console.log(character)
Solution 20 - Javascript
In today's JavaScript you can
Obviously, c+c represents whatever you want to do with c.
This returns
"mm", "yy", " ", "ss", "tt", "rr", "ii", "nn", "gg"]```
Solution 21 - Javascript
This should work in older browsers and with UTF-16 characters like ο©.
This should be the most compatible solution. However, it is less performant than a for
loop would be.
I generated the regular expression using regexpu
var str = 'My String π© ';
var regEx = /(?:[\0-\uD7FF\uE000-\uFFFF]|[\uD800-\uDBFF][\uDC00-\uDFFF]|[\uD800-\uDBFF](?![\uDC00-\uDFFF])|(?:[^\uD800-\uDBFF]|^)[\uDC00-\uDFFF])/g
str.replace(regEx, function (char) {
console.log(char)
});
Hope this helps!
Solution 22 - Javascript
You can access single characters with str.charAt(index)
or str[index]
. But the latter way is not part of ECMAScript so you better go with the former one.
Solution 23 - Javascript
If you want to animate each character you might need to wrap it in span element;
var $demoText = $("#demo-text");
$demoText.html( $demoText.html().replace(/./g, "<span>$&</span>").replace(/\s/g, " "));
I think this is the best way to do it, then process the spans. ( for example with TweenMax)
TweenMax.staggerFromTo( $demoText.find("span"), 0.2, {autoAlpha:0}, {autoAlpha:1}, 0.1 );
Solution 24 - Javascript
Try this code
function myFunction() {
var text =(document.getElementById("htext").value);
var meow = " <p> <,> </p>";
var i;
for (i = 0; i < 9000; i++) {
text+=text[i] ;
}
document.getElementById("demo2").innerHTML = text;
}
</script>
<p>Enter your text: <input type="text" id="htext"/>
<button onclick="myFunction();">click on me</button>
</p>