评估vs IF语句（许多IF语句） [英] Eval vs IF statements (many IF statements)

问题描述

这个小提琴几乎解释了我要寻找的东西。我正在尝试找到一种最简单的方法，无需使用 eval 进行编码。我可以在没有 eval 的情况下做到这一点，但我认为我将不得不编写1000个IF语句。还是有其他方法？

This fiddle pretty much explains what I'm looking for. I'm trying to find the simplest way to go about coding something WITHOUT using eval. I can do it without eval but I think I will have to write 1000s of IF statements. Or is there another way?

http：// jsfiddle .net / 243rz8eq / 9 /

HTML

Eval way...<br>
<a href="javascript:core.launch('wins.a({x:1})');">Window-A</a><br>
<a href="javascript:core.launch('wins.b({x:1})');">Window-B</a><br>
<a href="javascript:core.launch('wins.c({x:1})');">Window-C</a><br><br>

Non-Eval way.  Requires if statement for each window (there will be thousands).  Or is there a simpler way I'm not seeing?<br>
<a href="javascript:core.launch_no_eval('window_a');">Window-A</a><br>
<a href="javascript:core.launch_no_eval('window_b');">Window-B</a><br>
<a href="javascript:core.launch_no_eval('window_c');">Window-C</a><br><br>

JavaScript

JavaScript

window.core = {
    launch: function(obj_string) {
        //we init a blank dhtmlxwindow and do some other things here, then...
        var x = eval("new " + obj_string); //fill dhtmlxwindow with proper content
    },
    launch_no_eval: function(id) {
        //we init a blank dhtmlxwindow and do some other things here, then...
        if (id==="window_a") var x = wins.a({x:1}); //fill dhtmlxwindow with proper content
        else if (id==="window_b") var x = wins.b({x:1}); //fill dhtmlxwindow with proper content
        else if (id==="window_c") var x = wins.c({x:1}); //fill dhtmlxwindow with proper content
        //and so on for literally thousands of items.
    }
};

window.wins = {
    a: function(args) {
        //this.myName = 'wins.a'; is used for the help topic.
        //DB contains columns: [item] / [helpurl]
        //Example Data: [wins.a] / [/help/gettingstarted.html]
        //That is why in this previous post (http://stackoverflow.com/q/28096922/3112803)
        //I was wanting to know if a function could know it's own name so I wouldn't
        //have to type this line below for 1000s of items.
        this.myName = 'wins.a';
        console.log('Window-A is now displayed. Use "'+this.myName+'" to make link to help topic.');
    },
    b: function(args) {
        this.myName = 'wins.b';
        console.log('Window-B is now displayed. Use "'+this.myName+'" to make link to help topic.');
    },
    c: function(args) {
        this.myName = 'wins.c';
        console.log('Window-C is now displayed. Use "'+this.myName+'" to make link to help topic.');
    }
};

推荐答案

另一种方法是重写当前用法通过<$ c访问对象属性 $ c>点符号，并使用括号符号。

Another approach would be to re-write the current usage of accessing object properties via the dot notation and use the bracket notation instead.

launch_no_eval:function(id) {
        //we init a blank dhtmlxwindow and do some other things here, then...
        if (id==="window_a") var x = wins.a({x:1}); //fill dhtmlxwindow with proper content
        else if (id==="window_b") var x = wins.b({x:1}); //fill dhtmlxwindow with proper content
        else if (id==="window_c") var x = wins.c({x:1}); //fill dhtmlxwindow with proper content
        //and so on for literally thousands of items.
    }

可以如下重写，

launch_no_eval:function(id) { 
        var x = wins[id]({x:1});
}

这意味着您的HTML标记可以更改为

This would mean your HTML markup can change from,

<a href="javascript:core.launch_no_eval('window_a');">Window-A</a><br>
<a href="javascript:core.launch_no_eval('window_b');">Window-B</a><br>
<a href="javascript:core.launch_no_eval('window_c');">Window-C</a><br><br>

至，

<a href="javascript:core.launch_no_eval('a');">Window-A</a><br>
<a href="javascript:core.launch_no_eval('b');">Window-B</a><br>
<a href="javascript:core.launch_no_eval('c');">Window-C</a><br><br>

如丹尼尔（Daniel）在下面的评论所述，假设您无法控制HTML标记，必须使用 window _＃值传入，然后您可以执行以下操作，

As Daniel commented below, assuming you have no control over the HTML markup and must use the window_# value being passed in then you could perform the following,

launch_no_eval:function(id) {
        // replace 'window_' with empty string to retrieve unique id
        var x = wins[id.replace('window_', '')]({x:1});
}

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