How can I convert a JavaScript string value to be in all lower case letters?
Example: "Your Name"
to "your name"
Use either toLowerCase or toLocaleLowerCase methods of the String object. The difference is that toLocaleLowerCase
will take current locale of the user/host into account. As per § 15.5.4.17 of the ECMAScript Language Specification (ECMA-262), toLocaleLowerCase
…
…works exactly the same as toLowerCase except that its result is intended to yield the correct result for the host environment’s current locale, rather than a locale-independent result. There will only be a difference in the few cases (such as Turkish) where the rules for that language conflict with the regular Unicode case mappings.
Example:
var lower = 'Your Name'.toLowerCase();
Also note that the toLowerCase
and toLocaleLowerCase
functions are implemented to work generically on any value type. Therefore you can invoke these functions even on non-String
objects. Doing so will imply automatic conversion to a string value prior to changing the case of each character in the resulting string value. For example, you can apply toLowerCase
directly on a date like this:
var lower = String.prototype.toLowerCase.apply(new Date());
and which is effectively equivalent to:
var lower = new Date().toString().toLowerCase();
The second form is generally preferred for its simplicity and readability. On earlier versions of IE, the first had the benefit that it could work with a null
value. The result of applying toLowerCase
or toLocaleLowerCase
on null
would yield null
(and not an error condition).
toLocaleUpperCase() or lower case functions don't behave like they should do.
For example in my system, Safari 4, Chrome 4 Beta, Firefox 3.5.x it converts strings with Turkish characters incorrectly.
The browsers respond to navigator.language as "en-US", "tr", "en-US" respectively.
But there is no way to get user's Accept-Lang setting in the browser as far as I could find.
Only Chrome gives me trouble although I have configured every browser as tr-TR locale preferred.
I think these settings only affect HTTP header, but we can't access to these settings via JS.
In the Mozilla documentation it says "The characters within a string are converted to ... while respecting the current locale.
For most languages, this will return the same as ...".
I think it's valid for Turkish, it doesn't differ it's configured as en or tr.
In Turkish it should convert "DİNÇ" to "dinç" and "DINÇ" to "dınç" or vice-versa.
Just an examples for toLowerCase()
, toUpperCase()
and prototype for not yet available toTitleCase()
or toProperCase()
String.prototype.toTitleCase = function() {
return this.split(' ').map(i => i[0].toUpperCase() + i.substring(1).toLowerCase()).join(' ');
}
String.prototype.toPropperCase = function() {
return this.toTitleCase();
}
var OriginalCase = 'Your Name';
var lowercase = OriginalCase.toLowerCase();
var upperCase = lowercase.toUpperCase();
var titleCase = upperCase.toTitleCase();
console.log('Original: ' + OriginalCase);
console.log('toLowerCase(): ' + lowercase);
console.log('toUpperCase(): ' + upperCase);
console.log('toTitleCase(): ' + titleCase);
edited 2018
I payed attention that lots of people are looking for strtolower()
in JavaScript. They are expecting the same function name as in other languages, that's why this post is here.
I would recommend using native Javascript function
"SomE StriNg".toLowerCase()
Here's the function that behaves exactly the same as PHP's one (for those who are porting PHP code into js)
function strToLower (str) {
return String(str).toLowerCase();
}
Note that the function will ONLY work on STRING objects.
For instance, I was consuming a plugin, and was confused why I was getting a "extension.tolowercase is not a function" JS error.
onChange: function(file, extension)
{
alert("extension.toLowerCase()=>" + extension.toLowerCase() + "<=");
Which produced the error "extension.toLowerCase is not a function" So I tried this piece of code, which revealed the problem!
alert("(typeof extension)=>" + (typeof extension) + "<=");;
The output was"(typeof extension)=>object<=" - so AhHa, I was NOT getting a string var for my input. The fix is straight forward though - just force the darn thing into a String!:
var extension = String(extension);
After the cast, the extension.toLowerCase() function worked fine.
Method or Function: toLowerCase(), toUpperCase()
Description: These methods are used to cover a string or alphabet from lower case to upper case or vice versa. e.g: "and" to "AND".
Converting to Upper Case:- Example Code:-
<script language=javascript>
var ss = " testing case conversion method ";
var result = ss.toUpperCase();
document.write(result);
</script>
Result: TESTING CASE CONVERSION METHOD
Converting to Lower Case:- Example Code:
<script language=javascript>
var ss = " TESTING LOWERCASE CONVERT FUNCTION ";
var result = ss.toLowerCase();
document.write(result);
</script>
Result: testing lowercase convert function
Explanation: In the above examples,
toUpperCase() method converts any string to "UPPER" case letters.
toLowerCase() method converts any string to "lower" case letters.
Opt 1: using toLowerCase()
var x = 'ABC';
x = x.toLowerCase();
Opt 2: Using your own function
function convertToLowerCase(str) {
var result = '';
for (var i = 0; i < str.length; i++) {
var code = str.charCodeAt(i);
if (code > 64 && code < 91) {
result += String.fromCharCode(code + 32);
} else {
result += str.charAt(i);
}
}
return result;
}
Call it as:
x = convertToLowerCase(x);
In case you want to build it yourself:
function toLowerCase(string) {
let lowerCaseString = "";
for (let i = 0; i < string.length; i++) {
//find ASCII charcode
let charcode = string.charCodeAt(i);
//if uppercase
if (charcode > 64 && charcode < 97){
//convert to lowercase
charcode = charcode + 32
}
//back to char
let lowercase = String.fromCharCode(charcode);
//append
lowerCaseString = lowerCaseString.concat(lowercase);
}
return lowerCaseString
}