Closure implementation iterator effect

iterator

Call a function repeatedly Will return different values But these values have some correlation For example, the number stored sequentially in the array

• Array iterator

var arr  = [1,2,3,4,5];
var next = (function(){
var index = 0;
return function(){
	if(index>=arr.length){
		throw new Error(" Unable to continue iteration ");
	}
	return arr[index++];
}
})()

next();//1
1
next();
2
next();
3
next();
4
next();
5
next();
VM871:6 Uncaught Error:  Unable to continue iteration 
    at <anonymous>:6:9
    at <anonymous>:1:1