Determine whether window. onload is used multiple times _ javascript tips-js tutorial

Window. onload must have been used by everyone. It is executed during window loading. How can we determine if window. onload is used multiple times? Next, I will share with you a method window. onload that must have been used by everyone. It is executed during window loading. How can we determine if window. onload is used multiple times? Take a look at the following code

Script function onloadCallback () {// Todo} if (window. onload) {var onload_random = 'onload' + Math. random (); window [onload_random] = window. onload; window. onload = function () {window [onload_random] (); onloadCallback () ;}}else {window. onload = function () {onloadCallback () ;};} script