onLoad

From "JavaScript: The Definitive Guide"

by Brock Callahan

JavaScript

// Register the function f to run when the document finishes loading
// If the document has already loaded, run it asynchronously ASAP.

function onLoad(f) {
    if (onLoad.loaded)                              // If document is already loaded
        window.setTimeout(f, 0);                    // Queue f to be run as soon as possible
    else if (window.addEventListener)               // Standard event registration method
        window.addEventListener("load", f, false);
    else if (window.attachEvent)                    // IE8 and earlier use this method
        window.attachEvent("onload", f);
}

// Start by setting a flag that indicates that the document is not loaded yet.
onLoad.loaded = false;

// And register a function to set the flag when the document does load.
onload(function() { onLoad.loaded = true });