Substitution of " " with "%20" in JS

I want to substitute a variable including " " with "%20" so I can use it in a link. How do I do that with a JS-function?

Code:

---

function subs(){
var strName= "This is the test";
}

---

And my result should be
"This%20ís%20the%20test"

try this perhaps

http://summerholiday.org/freecode/Ja...RL_Encode.html