Refer to the following code part which used rejex in javascript to remove duplicate white spaces.
function trim(value) {
var temp = value;
var obj = /^(\s*)([\W\w]*)(\b\s*$)/;
if (obj.test(temp)) { temp = temp.replace(obj, '$2'); }
var obj = / +/g;
temp = temp.replace(obj, " ");
if (temp == " ") { temp = ""; }
return temp;
}