jQuery 中是否有等效的 eval()？
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Is there an equivalent of eval() in jQuery?
提问by user1448031
I am trying to create dynamic variables in jQuery. I tried using eval()and it seems to work fine but I don't think eval()is a jQuery function. Is there an equilvant of eval()in jQuery? See my code here: http://jsfiddle.net/3CXgy/
我正在尝试在 jQuery 中创建动态变量。我尝试使用eval()它似乎工作正常，但我认为eval()它不是 jQuery 函数。eval()jQuery 中有 equilvant吗？在此处查看我的代码：http: //jsfiddle.net/3CXgy/
var test = function(pos) {
alert(eval('COUNT_'+pos));
}
var COUNT_LEFT = 20;
var COUNT_RIGHT = 30;
test('LEFT');
test('RIGHT');
Is there a different way to do this other than using eval()? I am not sure if eval()is perfectly fine in my example above.
除了使用之外，还有其他方法可以做到这一点eval()吗？我不确定eval()在我上面的例子中是否完全没问题。
回答by mplungjan
There are very rarely any reasons to use eval
很少有理由使用 eval
Here is your code assuming the vars were defined in the head
这是假设变量在头部定义的代码
var test = function(pos) {
alert(window['COUNT_'+pos]);
}
var COUNT_LEFT = 20;
var COUNT_RIGHT = 30;
test('LEFT');
test('RIGHT');
To not pollute the global namespace, use
为了不污染全局命名空间，请使用
var COUNT = {"left":20, "right":30 }
var pos = "left";
alert(COUNT[pos]);
回答by Ohgodwhy
I'd personally prefer to just store it in an object which we can easily access, add to, modify, and remove from anytime.
我个人更喜欢将它存储在一个我们可以随时轻松访问、添加、修改和删除的对象中。
var count = {
'left' : 20,
'right' : 30
}
var test = function(pos){
alert(count[pos]);
}
test('left');
test('right');
If you feel the need to use uppercase, just ensure you use a cohesive pattern, so switch it all to lowercase in the function.
如果您觉得需要使用大写字母，请确保使用有凝聚力的模式，因此在函数中将其全部切换为小写字母。
var test = function(pos){
alert(count[pos.toLowerCase()]);
}
回答by Denys Séguret
To access a global variable by its name, use this notation :
要按名称访问全局变量，请使用以下表示法：
window['COUNT_'+pos]
Usually you'd want to have your variable held in an object :
通常，您希望将变量保存在一个对象中：
var obj = {
COUNT_LEFT:20,
COUNT_RIGHT:30
}
and then you may access the "variables" as obj['COUNT_'+pos].
然后您可以将“变量”作为obj['COUNT_'+pos].
Your question as it is written lets think you don't really see what's jQuery. jQuery is a library providing useful functions that you use from your JavaScript code. You can't program in jQuery : you program in JavaScript using JavaScript functions, some of them being taken in the jQuery library.
您写的问题让您认为您并没有真正了解什么是 jQuery。jQuery 是一个库，提供您从 JavaScript 代码使用的有用函数。你不能在 jQuery 中编程：你使用 JavaScript 函数在 JavaScript 中编程，其中一些被 jQuery 库采用。
