JavaScript .replace only replaces first Match

textTitle.replace(/ /g, '%20');

From w3schools

The replace() method searches for a match between a substring (or regular expression) and a string, and replaces the matched substring with a new substring

Would be better to use a regex here then:

textTitle.replace(/ /g, '%20');

You need a /g on there, like this:

var textTitle = "this is a test";
var result = textTitle.replace(/ /g, '%20');

console.log(result);

You can play with it here, the default .replace() behavior is to replace only the first match, the /g modifier (global) tells it to replace all occurrences.