使用JavaScript循环数组并使用splice删除其所有元素？

Question

I am having an array of object. And I am looping every object and performing some operation and again in the end splice that element from that array. But I am not been able to achieve the desired result.

Here is what I have tried:

This is a sample array:

var arraylist=[{"username":"fzxd","contry":"vxcvxc"}, 
               {"username":"fzxdfsdf","contry":"vxcvxc"},
               {"username":"fsd","contry":"fsdf"},
               {"username":"fsdf","contry":"werr"}];
var l = arraylist.length;

for(var i = 0; i < l; i++)
{
  // For looping the item and doing some operation..
  console.log(arraylist[i].username + " " + arraylist.length);
  arraylist.splice(i,1); //In the end splicing it from the actual arraylist
}

When I run this only get fzxd 4 and fsd 3 printed on my log and not all elements. Where I am doing wrong? Please guide me. Thanks!

Answer 1

If you splice out the first element, the element that was at the second position is now at the first position, the element at the second position is the third one. Therefore you will skip the second one. Instead of accessing arraylist[i] take arraylist[0] as well as arraylist.splice(0, 1) . Or just:

  let users = [{ /*...*/ }, /*...*/ ];

  for(const user of users) {
    // do stuff with user
  }

  users = []; // clear array.

Answer 2

on last operation arraylist.length less then index ;

.splice it's side effect operation and after every calls as a result your index was moved and your array was changed.

 var arraylist = [{ "username": "fzxd", "contry": "vxcvxc" }, { "username": "fzxdfsdf", "contry": "vxcvxc" }, { "username": "fsd", "contry": "fsdf" }, { "username": "fsdf", "contry": "werr" }] var l = arraylist.length; for (var i = 0; i < l; i++) { //For looping the item and doing some operation.. console.log(arraylist.length, i) // on last operation arraylist.length less then index //console.log(arraylist[i].username + " " + arraylist.length); arraylist.splice(i, 1); //In the end splicing it from the actual arraylist } 

Answer 3

You can do it like this:

var arraylist = [{ "username": "fzxd", "contry": "vxcvxc" }, { "username": "fzxdfsdf", "contry": "vxcvxc" }, { "username": "fsd", "contry": "fsdf" }, { "username": "fsdf", "contry": "werr" }]
for(var i=arraylist.length-1; i>=0; i--)
{
  console.log(arraylist[i].username);
  arraylist.splice(i,1);
}

I hope this meets your requirement. Thanks!