{{jsSidebar("Objects")}}
Non-standard. The
Iterator function is a SpiderMonkey-specific feature, and will be removed at some point. For future-facing usages, consider using for..of loops and the iterator protocol.The Iterator function returns an object which implements legacy iterator protocol and iterates over enumerable properties of an object.
Syntax
Iterator(object, [keyOnly])
Parameters
object- Object to iterate over properties.
keyOnly- If
keyOnlyis truthy value,Iterator.prototype.nextreturnsproperty_nameonly.
Description
Returns Iterator instance that iterates over object. Iterator instance returns [property_name, property_value] array for each iteration if keyOnly is falsy, otherwise, if keyOnly is truthy, it returns property_name for each iteration. If object is the Iterator instance or {{jsxref("Generator")}} instance, it returns object itself.
Properties
Iterator.prototype[@@iterator]- Returns a function that returns iterator object, that conforms to {{jsxref("Iteration_protocols", "iterator protocol", "", 1)}}.
Methods
Iterator.prototype.next- Returns next item in the
[property_name, property_value]format orproperty_nameonly. It throwsStopIterationif there are no more items.
Examples
Iterating over properties of an object
var a = {
x: 10,
y: 20,
};
var iter = Iterator(a);
console.log(iter.next()); // ["x", 10]
console.log(iter.next()); // ["y", 20]
console.log(iter.next()); // throws StopIteration
Iterating over properties of an object with legacy destructuring for-in statement
var a = {
x: 10,
y: 20,
};
for (var [name, value] in Iterator(a)) {
console.log(name, value); // x 10
// y 20
}
Iterating with for-of
var a = {
x: 10,
y: 20,
};
for (var [name, value] of Iterator(a)) { // @@iterator is used
console.log(name, value); // x 10
// y 20
}
Iterates over property name
var a = {
x: 10,
y: 20,
};
for (var name in Iterator(a, true)) {
console.log(name); // x
// y
}
Passing Generator instance
function f() {
yield "a";
yield "b";
}
var g = f();
console.log(g == Iterator(g)); // true
for (var v in Iterator(g)) {
console.log(v); // a
// b
}
Passing Iterator instance
var a = {
x: 10,
y: 20,
};
var i = Iterator(a);
console.log(i == Iterator(i)); // true
Specifications
{{WhyNoSpecStart}}Non-standard. Not part of any current standards document.{{WhyNoSpecEnd}}
Browser compatibility
{{CompatibilityTable}}
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|
| Basic support | {{CompatNo}} | {{CompatVersionUnknown}} | {{CompatNo}} | {{CompatNo}} | {{CompatNo}} |
| Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|---|
| Basic support | {{CompatNo}} | {{CompatNo}} | {{CompatVersionUnknown}} | {{CompatNo}} | {{CompatNo}} | {{CompatNo}} |