短的方式来代替数组含量 [英] Short way to replace content of an array
问题描述
有没有更换一个数组的内容，并保持对它的引用任何方便的方式？我不想更换阵列是这样的：
VAR ARR1 = [1,2,3];
VAR referenceToArr1 = ARR1;
VAR ARR2 = [4,5,6];ARR1 = ARR2;
//日志：[4,5,6]假
的console.log（ARR1，ARR1 === referenceToArr1）;
//日志[1,2,3]
的console.log（referenceToArr1）;
本办法 ARR1 的 ARR2 的内容，但我失去的参考referenceToArr1 ，因为它仍然指向的原始的 ARR1 。
通过这种方式，我不松参考：
VAR ARR1 = [1,2,3];
VAR referenceToArr1 = ARR1;
VAR ARR2 = [4,5,6];arr1.length = 0;
对于（VAR I = 0; I＆LT; arr2.length;我++）{
arr1.push（ARR2 [I]）;
}
//日志：[4,5,6]真
的console.log（ARR1，ARR1 === referenceToArr1）;
//日志：[4,5,6]
的console.log（referenceToArr1）
在这里的缺点是，我得空 arr1.length = 0 ， ARR2 并用手把它推到 ARR1 。
我的问题是：
- 当然，我可以写这样的帮手，但什么是最有效的方法是什么？
- 是否有短，香草JavaScript的方式，这样做（也许是单行？）
- 我还使用underscore.js，但还没有找到这种问题的方法。有没有办法用underscore.js做到这一点？
背景：
我有一个服务的AngularJS应用。这里面的服务，我有一个数组，以保持从服务器加载的所有元素。从服务中的数据得到的绑定到一个控制器和视图中使用。当从服务中获得的变化数据（例如，重新读取发生），我想自动更新我的控制器VAR和它绑定视图。
这里是一个Plunker： http://plnkr.co/edit / 8yYahwDO6pAuwl6lcpAS？p = preVIEW
VAR应用= angular.module（'plunker'，[]）;app.controller（'MainCtrl'，函数（$范围，为myService）{
$ scope.name ='世界';
myService.fetchData（）。然后（功能（数据）{
的console.log（数据）
$ scope.data =数据;
}）
}）;app.service（'为myService'，函数（$超时，$ Q）{
VAR ARR;
VAR推迟; VAR loadData =功能（）{
//这里从服务器附带的一些数据
变种serverData = [1,2,3];
ARR = serverData;
deferred.resolve（ARR）; //模拟数据的重取
$超时（函数（）{
VAR newServerData = [4,5,6];
//这是行不通的，因为MainCtrl失去它的参考
// ARR = newServerData;
}，1000）; $超时（函数（）{
VAR newServerData = [7,8,9];
arr.length = 0;
[] .push.apply（ARR，newServerData）;
}，2000）; $超时（函数（）{
VAR newServerData = [10,11,12]。
[] .splice.apply（ARR，[0，arr.length] .concat（newServerData））;
}，3000）;
} 返回{
fetchData：功能（）{
递延= $ q.defer（）; loadData（）; 返回deferred.promise;
}
}
}）
和视图：
＆LT;！DOCTYPE HTML＆GT;
＆LT; HTML NG-应用=plunker＆GT; ＆LT; HEAD＆GT;
＆LT;间的charset =UTF-8/＆GT;
＆LT;标题＆GT; AngularJS Plunker＆LT; /标题＆GT;
＆LT;脚本＆GT;的document.write（'＆LT;基本href =+ document.location +'/＆GT;'）;＆LT; / SCRIPT＆GT;
＆LT;链接rel =stylesheet属性HREF =style.css文件/＆GT;
＆所述;脚本数据需要=angular.js@1.2.xSRC =的https：//$c$c.angularjs.org/1.2.16/angular.js数据semver =1.2.16＆GT ;＆LT; / SCRIPT＆GT;
＆所述; SCRIPT SRC =app.js＆GT;＆下; /脚本＆GT;
＆LT; /头＆GT; ＆LT;机身NG控制器=MainCtrl＆GT;
＆LT; UL＆GT;
＆LT;李NG重复=D数据＆GT; {{D}}＆LT; /李＆GT;
＆LT; / UL＆GT;
3每隔重新提取第二
＆LT; /身体GT;＆LT; / HTML＆GT;
这个是什么：
// 1.重置阵列，同时保持其基准
arr1.length = 0;
// 2.填充与来自第二项的第一阵列
[] .push.apply（ARR1，ARR2）;
请参阅：
Is there any convenient way to replace the content of an array, AND keep a reference to it? I don't want to replace the array like this:
var arr1 = [1,2,3];
var referenceToArr1 = arr1;
var arr2 = [4,5,6];
arr1 = arr2;
// logs: [4,5,6] false
console.log(arr1, arr1===referenceToArr1);
// logs [1,2,3]
console.log(referenceToArr1);
This way arr1 has the content of arr2, but I loose the reference in referenceToArr1, because it still points to the original arr1.
With this way, I don't loose the reference:
var arr1 = [1,2,3];
var referenceToArr1 = arr1;
var arr2 = [4,5,6];
arr1.length = 0;
for (var i = 0; i < arr2.length; i++) {
arr1.push(arr2[i]);
}
// logs: [4,5,6] true
console.log(arr1, arr1===referenceToArr1);
// logs: [4,5,6]
console.log(referenceToArr1)
The drawback here is, that I have to empty arr1.length = 0, iterate over every element of arr2 and push it to arr1 by hand.
My questions are:
- Sure, I could write a helper for this, but what is the most efficient way?
- Is there a short, vanilla javascript way, to do this (maybe a one liner?)
- I'm also using underscore.js but haven't found a method for this kind of problem. Is there a way to do this with underscore.js?
Background:
I have an AngularJS app with a service. Inside this service, I have an array to keep all the elements loaded from the server. The data from the service get's bind to a controller and is used in a view. When the data from the service get's change (e.g. a refetch happens), I want to auto update my controllers vars and the view it is bind to.
Here is a Plunker: http://plnkr.co/edit/8yYahwDO6pAuwl6lcpAS?p=preview
var app = angular.module('plunker', []);
app.controller('MainCtrl', function($scope, myService) {
$scope.name = 'World';
myService.fetchData().then(function(data) {
console.log(data)
$scope.data = data;
})
});
app.service('myService', function($timeout, $q) {
var arr;
var deferred;
var loadData = function() {
// here comes some data from the server
var serverData = [1,2,3];
arr = serverData;
deferred.resolve(arr);
// simulate a refetch of the data
$timeout(function() {
var newServerData = [4,5,6];
// this won't work, because MainCtrl looses it's reference
// arr = newServerData;
}, 1000);
$timeout(function() {
var newServerData = [7,8,9];
arr.length = 0;
[].push.apply(arr, newServerData);
}, 2000);
$timeout(function() {
var newServerData = [10,11,12];
[].splice.apply(arr, [0, arr.length].concat(newServerData));
}, 3000);
}
return {
fetchData: function() {
deferred = $q.defer();
loadData();
return deferred.promise;
}
}
})
And the view:
<!DOCTYPE html>
<html ng-app="plunker">
<head>
<meta charset="utf-8" />
<title>AngularJS Plunker</title>
<script>document.write('<base href="' + document.location + '" />');</script>
<link rel="stylesheet" href="style.css" />
<script data-require="angular.js@1.2.x" src="https://code.angularjs.org/1.2.16/angular.js" data-semver="1.2.16"></script>
<script src="app.js"></script>
</head>
<body ng-controller="MainCtrl">
<ul>
<li ng-repeat="d in data">{{d}}</li>
</ul>
3 refetches every second
</body>
</html>
What about this:
// 1. reset the array while keeping its reference
arr1.length = 0;
// 2. fill the first array with items from the second
[].push.apply(arr1, arr2);
See:
- How to empty an array in JavaScript?
- .push() multiple objects into JavaScript array returns 'undefined'
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