I think it should alert 4 times, but why it just alerted just 2 times. Is there anyone can make an explanation for me?
var arr = new Array;
arr.push("1");
arr.push("2");
arr.push("3");
arr.push("4");
for(var i=0;i<arr.length;i++){
alert(arr.pop());
}
Change your for loop to a while loop:
while(arr.length) {
alert(arr.pop());
}
The problem is that you remove elements from the array, so the length decreases, ending your for loop early. After 2 iterations of your for loop, arr.length is 2, and i is also 2, so the loop ends.
Here's a working example of the above.
for(var i = 0, l = arr.length; i < l; i++)Your code is checking length every Loop so in second loop array length must be 2 (2 poped) but var i is 2 so they'll out loop
Try to use for or you can use
var arr = new Array;
arr.push("1");
arr.push("2");
arr.push("3");
arr.push("4");
var length = arr.length;
for(var i=0;i<length;i++){
alert(arr.pop());
}
Pop removes the element from the array, and decreases the length property. So after two loop i = 2 and the array length = 2.
var arr = new Array;
arr.push("1");
arr.push("2");
arr.push("3");
arr.push("4");
var len = arr.length;
for(var i=0;i<len;i++){
alert(arr.pop());
}
due to pop() operation array length decrements during loop execution. So after 2 iterations, i==2 and arr.length==2
