change characters in a string javascript code example

Example 1: javascript replace string

var str = "JavaScript replace method test";
var res = str.replace("test", "success");  
//res = Javscript replace method success

Example 2: js replace characters in a string

var str = "Original string!";
var str = str.replace("Original", "New");

Example 3: replace all javascript

str.split(search).join(replacement);