angularjs forEach and splice

问题

I have an array like this:

$scope.emails = [
  {"key":"Work","value":"user@domine.com"},
  {"key":"","value":""},
   {"key":"Work","value":"user2@domine.com"}
  {"key":"","value":""}];

So, I want to remove empty emails but angular forEach method removing only one object that is last object why???.

js code

angular.forEach($scope.emails, function(email, index){
     if(email.value ===""){
       $scope.emails.splice(index, 1);

     } 

    });

where I am doing wrong

JS Bin

回答1:

The problem is that you remove elements from the array during the loop so later items are at different indices. You need to loop backwards instead:

for (var i = $scope.emails.length - 1; i >= 0; i--) {
    if (!$scope.emails[i].value) {
        $scope.emails.splice(i, 1);
    }
}

Here's an updated example.

回答2:

Like others have pointed out, the culprit of the code is the array got removed. To get around with angular.forEach, you can try the additive/assignment approach:

var filteredEmails = [];
angular.forEach($scope.emails, function(email, index){
    if(email.value !==""){
        filteredEmails.push(email);
    }
});

$scope.emails = filteredEmails;

回答3:

indexOf returns -1 when it doesn't find an item.

A way to remove an item, and to avoid removing the last one when not found, is:

var index = $scope.items.indexOf($scope.oldItem);

if (index != -1) {
  $scope.items.splice(index, 1);
}

回答4:

describe('Foreach Splice', function () {
  it('splicing', function () {

    var elements = [
      {name: "Kelly", age: 16},
      {name: "", age: 17},
      {name: "Becky", age: 18},
      {name: "", age: 18},
      {name: "Sarah", age: 19},
      {name: "", age: 20},
      {name: "", age: 22},
      {name: "Mareck", age: 21},
      {name: "", age: 21},
      {name: "Mareck", age: 21}
    ];

    removeEmptyEntry(elements);
    console.log(elements);
  });


  function removeEmptyEntry(elements) {
    elements.forEach(function (element, index) {
      if (!element.name) {
        elements.splice(index, 1);
        removeEmptyEntry(elements);
      }
    });
  }
});

回答5:

I haven't tried this with AngularJs, but with Angular 4 a similar way of this works pretty well.

angular.forEach($scope.emails, function(email){
 if(email.value ===""){
   $scope.emails.splice($scope.emails.indexOf(email), 1);
 } 

});

Angular 4 version:

this.emailArray.forEach(email => {
  if (email.value == "") {
    this.emailArray.splice(this.emailArray.indexOf(email),1);
  }
});

回答6:

According to the docs, the iterator function allows a third parameter which is the collection which is being iterated. Splicing that collection instead of $scope.emails will remove the expected obejct.

angular.forEach($scope.emails, function(email, index, obj){
    if(email.value ===""){
        obj.splice(index, 1);
    } 
});

来源：https://stackoverflow.com/questions/24202962/angularjs-foreach-and-splice