// test.js //
var testObj = {};
testObj.init = function(){
console.log('google');
}
var onload = testObj.init;
/// what does it mean, does it mean it gets executed when script loaded or what, I just can't understand it as it is not looging into console anything under Google Chrome plugin...
Nothing is logged because you are simply setting onload to be a pointer to the function testObj.init which only gets the function's code. To actually run it, you must call testObj.init().
More about onload…
onload is a property of an HTML element that can be set to run javascript. For example:
<html>…
… <body onload="testObj.init()"> …
…</html>
This means that when the "body" element is loaded, the function testObj.init() is run.
The "onload" property can also be attatched by javascript, as in:
window.onload=myFunction();
It just means that your variable onload now points to
function(){
console.log('google');
}
onload is just the name of a local variable here.
In your code, onload is simply the name of a local variable. The var keyword declares local variables. You're setting the value of onload to testObj.init, which is a function that prints 'google' to the console.
To make it run the function on page load, set window.onload to the value of the function.
window.onload = testObj.init;
Or, better yet, use event handlers to attach an "onload" event to the window object. (To make this easier, use a JavaScript library such as jQuery, but I recommend you first learn how it all works.)
It means that variable onload is a reference to the function testObj.init. onload() will execute the function and output 'google' to the console.
No, it only means that you assign it to a variable named onload.
Depending on the scope of the code it might actually work, if the variable name collides with the onload property of the window object. In that case a variable would not be created, but it would use the existing property instead. You should not rely on this behaviour though, you should always specify it as a property of the object:
window.onload = testObj.init;
Think of it like giving your dog 2 names:
var spot = new Dog();
var comeHereSpot = function () { return spot; }
var comeHereBoy = comeHereSpot;
Whether you call comeHereSpot or comeHereBoy the same dog will come running.