Increment a number on each replace in javascript

Question

I want to increment a number each time string.replace() replace a sub-string. for example in:

var string = "This is this";
var number = 0;
string.replace("is", "as");

When string.replace first is of This number becomes 1, then for second is of is number becomes 2 and finally for last is of this number becomes 3. Thanks in advance...! :-)

Answer 1

You can pass a function to .replace() and return the value. You also need to use a global regex to replace all instances.

var string = "This is this";
var number = 0;

document.body.textContent = string.replace(/is/g, function() {
    return ++number;
});

Answer 2

Try:

var string = "This is this";
var number = 0;
string.replace(/is/g, function() {
  number++;
  return "as";
});
alert(number);