how to loop through JavaScript Array member functions, the following code doesn't work :(
for (var i in Array.prototype){
alert(i)
} //show nothing
for (var i in []){
alert(i)
} // show nothing
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2 Answers
None of the native prototypal properties are enumerable, but you can find out exactly what you're looking for in the ECMA spec:
http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-262.pdf
You can only enumerate through properties which you defined, eg:
Object.prototype.foo = function(){};
x = {};
for ( var prop in x ) {
alert( prop );
}
would alert:
foo
Another useful tip is that you can use object.hasOwnProperty( property ) inside a for..in loop to branch only if the object directly owns a property, and the property does not descend from the constructor's prototype, of which all objects pretty much descend from Object.prototype.
Comments
You can't loop through native methods.
