Finding a substring and inserting another string

Question

Suppose I have string variable such as:

var a = "xxxxxxxxhelloxxxxxxxx";

or:

var a = "xxxxhelloxxxx";

I want to insert "world" after "hello".

I can't use substr() because the position is not known ahead of time. How can I do this in JavaScript or jQuery?

Answer 1

var a = "xxxxhelloxxxxhelloxxxx";
a = a.replace(/hello/g,"hello world"); // if you want all the "hello"'s in the string to be replaced
document.getElementById("regex").textContent = a;

a = "xxxxhelloxxxxhelloxxxx";
a = a.replace("hello","hello world"); // if you want only the first occurrence of "hello" to be replaced
document.getElementById("string").textContent = a;

<p>With regex: <strong id="regex"></strong></p>
<p>With string: <strong id="string"></strong></p>