JSON密钥称为“ true”，无法在JavaScript中引用（JSfiddle示例）

Question

First of all, I converted a Plist(XML formatted) to JSON with some online tool, this isn't the problem. I managed to pick the important values from this rather big JSON file. With this important information I am rebuilding a new JSON file that is very lean and contains information I can use for a plug-in — that I will create later.

The plist conversion to JSON is ugly. At some point <true/> and <false/> are converted to JSON, leaving this in the JSON: "false":"", or "true":"", .

I am using jQuery

check JSfiddle for an example jsfiddle example

or here

// Simplified (not really a JSON file, but this will do it for explaining) 
var themeJSON = {
    "item": {
        "false": "",
    },
};

// I need to know if its enabled: "true" or disabled: "false"

// function for checking if this is the default option
function checkDefault() {
    // true is a keyword!
    if (themeJSON.item.true) {
        return "1";
    // so is false!
    } else(themeJSON.item.false) {
        return "0";
    }
}

Maybe I use some other function such as find() ?

updated for answer: thanks to the comments, this is what I have now:

function checkDefault() {
    if (item.hasOwnProperty("true")) {
        return "1";
    } else if(item.hasOwnProperty("false")) {
        return "0";
    }
}

Answer 1

Try using the property name as a string:

if (themeJSON.item['true']) {
  return '1';
}
else if (themeJSON.item['false']) {
    return "0";
}

edit — a comment correctly points out that though accessing the properties by string value will indeed work, your code is otherwise flawed. If the properties are really being given empty string values, then what you really need is a way to test whether the property is there at all, and not (as this code does) just check the value of the property:

if (typeof themeJSON.item['true'] !== 'undefined') { ... }

or, alternatively:

if ('true' in themeJSON.item) { ... }

An explicit check for equality against the empty string would do too:

if (themeJSON.item['true'] === '') { ... }

Answer 2

When an object property has a name which is a reserved keyword, the array index notation can be used to reference it.

A way of checking whether item has a property named false :

> themeJSON.item.hasOwnProperty("false");
true

This not ideal because a single object could have both a false property and a true property.

Answer 3

In JS, foo.bar is the equivalent of foo['bar'] . Therefose:

if (themeJSON.item['true'] === "")

Note the need for === as false == "" but false !== "" .

Also, I must nitpick. themeJSON is no longer JSON since it's not a string - it's just another JavaScript object. You shouldn't confuse those two.

Answer 4

Try this code

function checkDefault() {
    // true is a keyword!
    if ("true" in themeJSON.item) {
        return "1";
    // so is false!
    } else if ("false" in themeJSON.item) {
        return "0";
    }
}