How to remove duplicate white spaces in a string?

Question

Possible Duplicate:
Replace multiple whitespaces with single whitespace in JavaScript string

I have used trim function to remove the white spaces at the beginning and end of the sentences. If there is to much white spaces in between words in a sentence, is there any method to trim?

for example

"abc                  def. fds                            sdff."

Answer 1

try

"abc                  def. fds                            sdff."
 .replace(/\s+/g,' ')

or

"abc                  def. fds                            sdff."
     .split(/\s+/)
     .join(' ');

or use this allTrim String extension

String.prototype.allTrim = String.prototype.allTrim ||
     function(){
        return this.replace(/\s+/g,' ')
                   .replace(/^\s+|\s+$/,'');
     };
//usage:
alert(' too much whitespace     here   right?  '.allTrim());
   //=> "too much whitespace here right?"

[edit 2023] Pretty old answer. Here is a parser function to remove all multiple spaces (and spaces only, not whitespace) from a string, which removes the need for a regular expression.

const line = ` hello     world
          how  are    you
       
    😃 and bye again  `;

console.log(`[${removeDoubleSpaces(line)}]`);
console.log(`[${removeDoubleSpaces(line, true)}]`);
console.log(`[${removeDoubleSpaces(line, true, true)}]`);
console.log(`[${removeDoubleSpaces(line, false, true)}]`);

function removeDoubleSpaces(str, trimLines = false, removeLF = false) {
  let strResult = ``;
  const strCopy = [...str];
  
  while(strCopy.length) {
    const chr = strCopy.shift();
    strResult += removeLF && chr === `\n`  ? ` ` :
      strResult.at(-1) + chr !== `  ` ? chr : ``;
    // double line ends may result in double spaces
    strResult = strResult.slice(-2) === `  `
      ? strResult.slice(0, -1) : strResult;
  }
  
  return trimLines
    ? strResult.split(/\n/).map(v => v.trim()).join(`\n`)
    : strResult.trim();
 
 
}

.as-console-wrapper {
    max-height: 100% !important;
}