how to add double quotes to a string before javascript code example

Example 1: javascript escape single quote

document.getElementById("something").innerHTML = "<img src='something' onmouseover='change(\"ex1\")' />";

Example 2: javascript escape single quote

var string = 'this isn\'t a double quoted string';
var string = "this isn\"t a single quoted string";
//           ^         ^ same types, hence we need to escape it with a backslash