Reasonably portable, non-framework way of having your script set a function to run at load time

genericOnLoadEvent.js

/**
 * @source http://stackoverflow.com/questions/807878/javascript-that-executes-after-page-load#807997
 */
var yourFunctionName = function(){};

if(window.attachEvent) {
    window.attachEvent('onload', yourFunctionName);
} else {
    if(window.onload) {
        var curronload = window.onload;
        var newonload = function() {
            curronload();
            yourFunctionName();
        };
        window.onload = newonload;
    } else {
        window.onload = yourFunctionName;
    }
}