How to convert "camelCase" to "Camel Case"?

Question

I’ve been trying to get a JavaScript regex command to turn something like "thisString" into "This String" but the closest I’ve gotten is replacing a letter, resulting in something like "Thi String" or "This tring". Any ideas?

To clarify I can handle the simplicity of capitalizing a letter, I’m just not as strong with RegEx, and splitting "somethingLikeThis" into "something Like This" is where I’m having trouble.

Answer 1

"thisStringIsGood"     // insert a space before all caps     .replace(/([A-Z])/g, ' $1')     // uppercase the first character     .replace(/^./, function(str){ return str.toUpperCase(); }) 

displays

This String Is Good 

(function() {      const textbox = document.querySelector('#textbox')    const result = document.querySelector('#result')    function split() {        result.innerText = textbox.value          // insert a space before all caps          .replace(/([A-Z])/g, ' $1')          // uppercase the first character          .replace(/^./, (str) => str.toUpperCase())      };      textbox.addEventListener('input', split);    split();  }());

#result {    margin-top: 1em;    padding: .5em;    background: #eee;    white-space: pre;  }

<div>    Text to split    <input id="textbox" value="thisStringIsGood" />  </div>    <div id="result"></div>

Answer 2

I had an idle interest in this, particularly in handling sequences of capitals, such as in xmlHTTPRequest. The listed functions would produce "Xml H T T P Request" or "Xml HTTPRequest", mine produces "Xml HTTP Request".

function unCamelCase (str){     return str         // insert a space between lower & upper         .replace(/([a-z])([A-Z])/g, '$1 $2')         // space before last upper in a sequence followed by lower         .replace(/\b([A-Z]+)([A-Z])([a-z])/, '$1 $2$3')         // uppercase the first character         .replace(/^./, function(str){ return str.toUpperCase(); }) } 

There's also a String.prototype version in a gist.