Convert JavaScript String to be all lower case?

Convert JavaScript String to be all lower case?

How can I convert a JavaScript string value to be in all lower case letters?
Example: “Your Name” to “your name”

Solutions/Answers:

Solution 1:

var lowerCaseName = "Your Name".toLowerCase();

Solution 2:

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).

Solution 3:

Yes, any string in JavaScript has a toLowerCase() method that will return a new string that is the old string in all lower case. The old string will remain unchanged.

So, you can do something like:

"Foo".toLowerCase();
document.getElementById('myField').value.toLowerCase();

Solution 4:

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.

Solution 5:

Just an examples for toLowerCase(), toUpperCase() and prototype for not yet available toTitleCase() or toPropperCase()

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

Solution 6:

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();
}