how to remove part of string in javascript code example

Example 1: remove substring from string javascript

var ret = "data-123".replace('data-','');

Example 2: how to remove part of string in javascript

var str = "test_23";
alert(str.split("_").pop());
// -> 23

var str2 = "adifferenttest_153";
alert(str2.split("_").pop());
// -> 153