Convert kebab-case to camelCase with JavaScript

Question

Say I have a function that transforms kebab-case to camelCase :

camelize("my-kebab-string") === 'myKebabString';

I'm almost there, but my code outputs the first letter with uppercase too:

function camelize(str){
  let arr = str.split('-');
  let capital = arr.map(item=> item.charAt(0).toUpperCase() + item.slice(1).toLowerCase());
  let capitalString = capital.join("");

  console.log(capitalString);
}
    
camelize("my-kebab-string");

Answer 1

You can also try regex.

camelize = s => s.replace(/-./g, x=>x[1].toUpperCase())

Looks only for hyphen followed by any character, and capitalises it and replaces the hyphen+character with the capitalised character.

Answer 2

To keep your existing code, I've just added a check on the index that will return item instead of the transformed item if item is 0 (falsy), since the problem is just that you are upper-casing the first item as well, while you shouldn't.

In a nutshell, the inline expression becomes: (item, index) => index ? item.charAt(0).toUpperCase() + item.slice(1).toLowerCase() : item (item, index) => index ? item.charAt(0).toUpperCase() + item.slice(1).toLowerCase() : item , because:

• If index is not falsy (so, if index is > 0 in your context), the capitalized string is returned.
• Otherwise, the current item is returned.

Of course, this could be cleaner and likely single line, but I wanted to stay as close as possible to your code so that you could understand what was wrong:

 function camelize(str){ let arr = str.split('-'); let capital = arr.map((item, index) => index ? item.charAt(0).toUpperCase() + item.slice(1).toLowerCase() : item.toLowerCase()); // ^-- change here. let capitalString = capital.join(""); console.log(capitalString); } camelize("my-kebab-string");

As a side note, you could've found a potential cleaner answer here: Converting any string into camel case

Answer 3

对于lodash用户：

_.camelCase('my-kebab-string') => 'myKebabString'

Answer 4

The first method is to just transform to lower case the first entry of your capital array, like this:

capital[0] = capital[0].toLowerCase();

Another method, which I think to be more efficient, is to pass another parameter to the map callback, which is the index . Take a look at this for further reading: https://www.w3schools.com/jsref/jsref_map.asp

So you transform to upper case only if (index > 0) . Like this:

let capital = arr.map((item, index) => index ? item.charAt(0).toUpperCase() + item.slice(1).toLowerCase() : item);

Answer 5

so I tried both array-string and regex but regex is slower !

 const string = " background-color: red; \n color: red;\n z-index: 10" // regex console.time("regex") let property = string const camelProp = property.replace(/(-[az])/, (g) => { return g.replace("-", "").toUpperCase() }) console.timeEnd("regex") // custom console.time("custom") const str = string let strNew = str .split("-") .map((e) => { return e[0].toUpperCase() + e.slice(1) }) .join("") console.timeEnd("custom") console.log(camelProp) console.log(strNew)