有条件地设置对象属性 [英] Conditionally set an object property

问题描述

是否有一些基于条件设置属性的语法？

Is there some syntax for setting properties based on a condition?

data: {
    userId: 7,
    actionId: 36,
    express: (myCondition ? true : null) // does not work
}

我希望 express 设置为一个值或者根本不设置（即，应该没有名为<$ c的键$ c> express ），定义后没有额外的陈述。我知道我可以将它用作布尔值，但接收端使用 isset（）检查，我想知道是否可以避免修改它。

I want express to be either set to a value or not set at all (i.e., there should be no key named express), and without extra statements after the definition. I know I can use it as a boolean, but the receiving side is using an isset() check and I'm wondering if I can avoid modifying it.

编辑：似乎没有直接解决问题的方法。以下是密切的建议：

Edit: Seems there is no direct solution to the problem as stated. Here are the close suggestions:

JSON.stringify （Chris Kessel，dystroy）：

JSON.stringify (Chris Kessel, dystroy):

var json = JSON.stringify( {
    data: {
        userId: 7,
        actionId: 36,
        express: (myCondition ? true : null)
    }
});

匿名函数（Paulpro）：

An anonymous function (Paulpro):

var data = new function(){
    this.userId = 7;
    this.actionId = 36;
    myCondition && (this.express = true);
};

额外声明（x4rf41）：

data: {
    userId: 7,
    actionId: 36
}
if(myCondition) data["express"] = true;

Eval （我以前的同事）：

eval("data = {userId: 7, actionId: 36 " + (myCondition ? ", express: true}" : "}"))

条件定义（真的不知道如何标记这个） ：

Conditional definition (don't really know how to label this one):

data = (
    (myCondition && { userId: 7, actionId: 36, express: true }) ||
    (!myCondition && { userId: 7, actionId: 36 })
);

推荐答案

这样做：

data: {
    userId: 7,
    actionId: 36,
    express: (myCondition ? true : undefined)
}

价值未定义的物业 stringify 对象时，不会写入$ c>到JSON。

A property whose value is undefined isn't written when you stringify the object to JSON.

编辑：从评论中可以看出，实际上没有涉及JSON。 OP使用 $ .ajax 因此可能使用 $ .param 。不幸的是， $ .param 确实为值为 undefined 的属性创建了一个条目。所以没有任何补充代码行可能没有解决方案。

EDIT : It appears from the comments that there is no JSON involved in fact. OP is using $.ajax so $.param is probably used. $.param, unfortunately, does create an entry for properties whose value is undefined. So there's probably no solution without any supplementary line of code.

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