AngularJS push item to first or 0 index of $scope array

问题

Please help me implement this function. I have an array of items in my $scope. Now, when I click on the Add Item button, I want to push a new item to the first index or 0 index of that array. Thanks in advance. :)

Here's a working jsFiddle to start with: http://jsfiddle.net/limeric29/7FH2e/

HTML:

<div ng-controller="Ctrl">
    {{data}}<br/>
    <input type="button" ng-click="addItem()" value="Add Item" />
</div>

JavaScript:

function Ctrl($scope) {
    $scope.data = [
    new String('Item 5'), new String('Item 4'), new String('Item 3'), new String('Item 2'), new String('Item 1')];

    $scope.addItem = function () {
        var c = $scope.data.length + 1;
        var item = new String('Item ' + c)
        $scope.data.push(item);
    };
}

回答1:

You can use the unshift function.

function Ctrl($scope) {
$scope.data = [
new String('Item 5'), new String('Item 4'), new String('Item 3'), new String('Item 2'), new String('Item 1')];

$scope.addItem = function () {
    var item = new String('Item ' + c)
    $scope.data.unshift(item);
};
}

回答2:

Solved my problem by using splice() instead of push() and assigning to what array index to insert.

HTML:

<div ng-controller="Ctrl">
    <pre>{{data}}</pre><br/>
    <input type="button" ng-click="addItem()" value="Add Item" />
</div>

Javascript:

function Ctrl($scope) {
    $scope.data = [
    new String('Item 4'), new String('Item 3'), new String('Item 2'), new String('Item 1')];

    $scope.addItem = function () {
        var c = $scope.data.length + 1;
        var item = new String('Item ' + c)
        $scope.data.splice(0, 0, item);
    };
}

Here's the updated fiddle for this. http://jsfiddle.net/limeric29/xvHNe/

回答3:

$scope.data.unshift(item);

One line, not sure why the others made it so difficult

回答4:

Try this:

function Ctrl($scope) {
    $scope.data = [
    new String('Item 4'), new String('Item 3'), new String('Item 2'), new String('Item 1')];

    $scope.addItem = function () {
        var c = $scope.data.length + 1;
        var item = new String('Item ' + c);
        $scope.data.push(item);
    };
}

回答5:

I think, not necessary this operation. You can solve it like this;

<div ng-controller="Ctrl">
    <!-- "$index" is short parameter, "true" statment is reverse parameter -->
    {{data | reverse:$index:true}}<br/>
    <input type="button" ng-click="addItem()" value="Add Item" />
</div>

来源：https://stackoverflow.com/questions/17826766/angularjs-push-item-to-first-or-0-index-of-scope-array

标签

javascript

angularjs

angularjs-scope