Question

This simple fiddle shows properties of Window object:

var obj = this; // object Window
var variables = "";
for (var name in obj) {
    if (obj.hasOwnProperty(name)) {
        variables += name + " : " + obj[name] + "<br/>";
    }
}
document.writeln(variables);

When this script is called directly with no wrap it shows this result:

window : [object Window]
document : [object HTMLDocument]
InstallTrigger : [object Object]
obj : [object Window]
variables : window : [object Window]  document : [object HTMLDocument]  InstallTrigger : [object Object] obj : [object Window]
name : name
getInterface : function getInterface() { [native code] }
location : http://fiddle.jshell.net/_display/
navigator : [object Navigator]

But when called onload it shows only:

window : [object Window]
document : [object HTMLDocument]
InstallTrigger : [object Object]
getInterface : function getInterface() { [native code] }
location : http://fiddle.jshell.net/4x3Tx/2/show/
navigator : [object Navigator]

And so the question is obvious: can somebody explain why are obj, variables and name variables missing from the second fiddle results? In both cases the obj refers to Window object.

Answer 1

When you run the code “onLoad”, it is put inside a function and assigned to window.onload:

window.onload=function(){
    var obj = this;
    var variables = "";
    for (var name in obj) {
        if (obj.hasOwnProperty(name)) {
            variables += name + " : " + obj[name] + "<br/>";
        }
    }
    document.writeln(variables);
    console.log(obj);
}

obj, variables and name are now local to that function, not global and hence are not properties of the window object.