javascript - 在Javascript中将数组分为两部分

Question

我有一个包含 N 个元素的数组。我想分成两个数组。唯一的条件是第一个新数组由原始数组的前三个元素组成，第二个新数组必须包含所有其他元素。 例如，原始数组包含["a","b","c","d","e","f","g","h"]。我想创建两个新数组:

first new array: ["a, "b", "c"];
second new array: ["d","e","f", "g","h"].

但是我的代码将原始数组划分了很多时间。为什么？

function MyCtrl($scope) {
$scope.strengthChartData = ["Banana", "Orange", "Apple", "Mango", "asd", "lol", "ahhhaha", "llllll", "ehhehehe", "oooo", "aaaaa", "bbbbbbbb"];

$scope.arrays = [];
var size = 3;

while ($scope.strengthChartData.length > 0)
    $scope.arrays.push($scope.strengthChartData.splice(0, size));
}

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app ng-controller="MyCtrl">
    <h3>All elements:</h3>
    <br>
    <ul>
        <li ng-repeat="array in arrays">{{array}}</li>
    </ul>
    
    <h3>First array:</h3>
    <br>
    <ul>
        <li ng-repeat="array in arrays[0]">{{array}}</li>
    </ul>

    <h3>Second array:</h3>
    <br>
    <ul>
        <li ng-repeat="array in arrays[1]">{{array}}</li>
    </ul>
</div>

Answer 1

您可以使用splice() 为此

var arr = ["a", "b", "c", "d", "e", "f", "g", "h"],
  arr1 = arr.splice(3);

document.write(JSON.stringify(arr) + '<br/>' + JSON.stringify(arr1));

---

更新:如果您不想更新原始数组，则 创建新数组并应用 splice() 或使用 slice()

使用 slice()仅

var arr = ["a", "b", "c", "d", "e", "f", "g", "h"],
  arr1 = arr.slice(0, 3);
arr2 = arr1.slice(3);

document.write(JSON.stringify(arr) + '<br/>' +
  JSON.stringify(arr1) + '<br/>' +
  JSON.stringify(arr2));

---

使用 splice() 和 slice() 不带任何参数复制所有元素

var arr = ["a", "b", "c", "d", "e", "f", "g", "h"],
  arr1 = arr.slice();
arr2 = arr1.splice(3);

document.write(JSON.stringify(arr) + '<br/>' +
  JSON.stringify(arr1) + '<br/>' +
  JSON.stringify(arr2));