How do I replace a character at a particular index in JavaScript?

Question

I have a string, let\'s say Hello world and I need to replace the char at index 3. How can I replace a char by specifying a index?

var str = \"h         


        

Answer 1

In JavaScript, strings are immutable, which means the best you can do is to create a new string with the changed content and assign the variable to point to it.

You'll need to define the replaceAt() function yourself:

String.prototype.replaceAt = function(index, replacement) {
    return this.substr(0, index) + replacement + this.substr(index + replacement.length);
}

And use it like this:

var hello = "Hello World";
alert(hello.replaceAt(2, "!!")); // Should display He!!o World