Javascript 如何获取对象的所有属性？

How to get all properties of an object?

提问by IAdapter

How to get all properties of an object using reflection in JavaScript?

如何在 JavaScript 中使用反射获取对象的所有属性？

回答by Daff

Loop through the object and take every key that belongs to it and is not a function:

循环遍历对象并获取属于它的每个键而不是函数：

var properties = [];
for(var key in obj) {
    if(obj.hasOwnProperty(key) && typeof obj[key] !== 'function') {
        properties.push(key);
    }
}

回答by Daff

In modern browsers, to get all property names (not just enumerable properties), you'd use Object.getOwnPropertyNames...

在现代浏览器中，要获取所有属性名称（不仅仅是可枚举的属性），您可以使用Object.getOwnPropertyNames...

var props = Object.getOwnPropertyNames(my_object)

If you don't want enumerable properties, you'd use Object.keys...

如果您不想要可枚举的属性，则可以使用Object.keys...

var props = Object.keys(my_object)

回答by PADYMKO

The JavaScript has no good, built-in tools for the reflection (introspection), so you need made it manually.

JavaScript 没有用于反射（内省）的好的内置工具，因此您需要手动进行。

At first, here a code of a solution

首先，这里有一个解决方案的代码

/**
 * Display details about an object at run-time
 * @param  {[any]} target Any object
 * @return Nothing, all information will be display
 */
const introspect = (target) => {
    // get type of a target
    const typeTarget = typeof target;

    // variable for type attribute of the target
    let typeAttr;

    // for properties and methods of the target
    let properties = [];
    let methods = [];

    // if target is array, keep names all enumerable properties, simple put - numbers of indexes
    // otherwise set to null
    const enumerableProperties = Array.isArray(target) ? Object.keys(target) : null;

    // determination functions and properties of the target by a parent object
    Object.getOwnPropertyNames(Object.getPrototypeOf(target)).forEach((name) => {
        if (typeof target[name] === 'function') {
            methods.push(name);
        } else if (target.hasOwnProperty(name) && properties.indexOf(name) === -1) {
            properties.push(name);
        }
    });

    // determination other functions and properties of the target
    // filter it, if a name already added or if it is an array - filter all values of the indexes
    Object.getOwnPropertyNames(target).forEach((name) => {
        if (enumerableProperties !== null && enumerableProperties.indexOf(name) !== -1) {
            return;
        }
        if (typeof target[name] === 'function') {
            methods.push(name);
        } else if (target.hasOwnProperty(name) && properties.indexOf(name) === -1) {
            properties.push(name);
        }
    });

    // order properties and methods by name in reverse
    properties = properties.reverse();
    methods = methods.reverse();

    // display an obtained information by groups
    console.log(`${typeTarget}: "${target}"`);
    console.log(`\n\tProperties: ${properties.length}\n\t------------------`);
    for (let i = properties.length - 1; i >= 0; i -= 1) {
        typeAttr = typeof target[properties[i]];
        console.log(`\t\t${properties[i]} --> ${typeAttr}`);
    }

    console.log(`\n\tMethods: ${methods.length}\n\t------------------`);
    for (let i = methods.length - 1; i >= 0; i -= 1) {
        let args = functools.getFunctionParameters(target[methods[i]]);
        args = args.join(', ');
        console.log(`\t\t${methods[i]} (${args})`);
    }
};

Examine this function on real examples.

在真实示例中检查此函数。

For built-in object Array

对于内置对象数组

introspect(Array);

Result:

结果：

function: "function Array() { [native code] }"

    Properties: 5
    ------------------
        length --> number
        name --> string
        arguments --> object
        caller --> object
        prototype --> object

    Methods: 8
    ------------------
        apply ()
        bind ()
        call ()
        toString ()
        constructor ()
        isArray ()
        from ()
        of ()

For real array (instance of object Array)

对于真实数组（对象数组的实例）

introspect([-10, '20', true, []]);

Result:

结果：

object: "-10,20,true,"

    Properties: 1
    ------------------
        length --> number

    Methods: 29
    ------------------
        constructor ()
        toString ()
        toLocaleString ()
        join ()
        pop ()
        push ()
        reverse ()
        shift ()
        unshift ()
        slice ()
        splice ()
        sort ()
        filter ()
        forEach ()
        some ()
        every ()
        map ()
        indexOf ()
        lastIndexOf ()
        reduce ()
        reduceRight ()
        copyWithin ()
        find ()
        findIndex ()
        fill ()
        includes ()
        entries ()
        keys ()
        concat ()

What about a real object?

实物呢？

introspect({
    aa: 1,
    bb: true,
    cc: [],
    dd: {},
    c: (z, a= 2) => {},
    b: function(z   =  1, a=2) {},
    d: function(b, zzz) {},
});

Result:

结果：

object: "[object Object]"

    Properties: 4
    ------------------
        aa --> number
        bb --> boolean
        cc --> object
        dd --> object

    Methods: 14
    ------------------
        hasOwnProperty ()
        constructor ()
        toString ()
        toLocaleString ()
        valueOf ()
        isPrototypeOf ()
        propertyIsEnumerable ()
        __defineGetter__ ()
        __lookupGetter__ ()
        __defineSetter__ ()
        __lookupSetter__ ()
        c (z, a = 2)
        b (z = 1, a = 2)
        d (b, zzz)

This function also good work with the built-in modules. Make introspect the module Math.

此功能也可以很好地与内置模块配合使用。内省数学模块。

introspect(Math);

Result

结果

object: "[object Math]"

    Properties: 8
    ------------------
        E --> number
        LN10 --> number
        LN2 --> number
        LOG2E --> number
        LOG10E --> number
        PI --> number
        SQRT1_2 --> number
        SQRT2 --> number

    Methods: 46
    ------------------
        hasOwnProperty ()
        constructor ()
        toString ()
        toLocaleString ()
        valueOf ()
        isPrototypeOf ()
        propertyIsEnumerable ()
        __defineGetter__ ()
        __lookupGetter__ ()
        __defineSetter__ ()
        __lookupSetter__ ()
        acos ()
        asin ()
        atan ()
        ceil ()
        clz32 ()
        floor ()
        fround ()
        imul ()
        max ()
        min ()
        round ()
        sqrt ()
        trunc ()
        random ()
        abs ()
        exp ()
        log ()
        atan2 ()
        pow ()
        sign ()
        asinh ()
        acosh ()
        atanh ()
        hypot ()
        cbrt ()
        cos ()
        sin ()
        tan ()
        sinh ()
        cosh ()
        tanh ()
        log10 ()
        log2 ()
        log1p ()
        expm1 ()

Matter what pollute answer superfluous code, try do it yourself and see results

不管什么污染回答多余的代码，尝试自己做，看看结果

introspect(34.2313);
introspect(true);
introspect(Date);
introspect((new Date()));
introspect(String);
introspect('text');

For full code, I also show the function "getFunctionParameters" (in module "functools.js"), since it used it.

对于完整代码，我还展示了函数“getFunctionParameters”（在模块“functools.js”中），因为它使用了它。

/**
 * Return array paraments of a function
 * @param  {[function]} func function
 * @return {[array]}      parameters the functions
 *
 */
const getFunctionParameters = (func) => {
    if (typeof func !== 'function') {
        throw new Error('A argument is not function.');
    }
    const args = func.toString().match(/\((.*)\)/)[1];
    return args.split(',').map((arg) => {
        if (arg.indexOf('=') === -1) return arg.trim();
        return arg
            .split('=')
            .map(val => val.trim())
            .join(' = ');
    });
};

Notes:

笔记：

1. Weakly tested

2. Full code here https://github.com/setivolkylany/nodejs-utils

3. Good resource about it topic http://www.2ality.com/2011/01/reflection-and-meta-programming-in.html

4. Used the features of the ES6

1. 弱测试

2. 完整代码在这里https://github.com/setivolkylany/nodejs-utils

3. 关于它主题的好资源http://www.2ality.com/2011/01/reflection-and-meta-programming-in.html

4. 使用了 ES6 的特性

回答by Uri

var point = { x:5, y:8 };

for( var name in point ) {
    // name contains the property name that you want
    // point[name] contains the value
}