如何使用JavaScript中的反射获取对象的所有属性？
答案 0 :(得分：29)
遍历对象并获取属于它的每个键，而不是 功能：
var properties = [];
for(var key in obj) {
if(obj.hasOwnProperty(key) && typeof obj[key] !== 'function') {
properties.push(key);
}
}
答案 1 :(得分：20)
在现代浏览器中，要获取所有属性名称（不仅仅是可枚举属性），您可以使用Object.getOwnPropertyNames ...
var props = Object.getOwnPropertyNames(my_object)
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)
答案 2 :(得分：7)
JavaScript没有用于反射（内省）的良好内置工具，因此您需要手动完成。
首先，这里是解决方案的代码
/**
* 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})`);
}
};
在实例上检查此功能。
对于内置对象Array
introspect(Array);
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 ()
对于实数组（对象数组的实例）
introspect([-10, '20', true, []]);
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 ()
真实物体怎么样？
introspect({
aa: 1,
bb: true,
cc: [],
dd: {},
c: (z, a= 2) => {},
b: function(z = 1, a=2) {},
d: function(b, zzz) {},
});
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)
此功能也可以很好地与内置模块配合使用。内省模拟数学。
introspect(Math);
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 ()
问题是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');
对于完整代码，我还会显示函数＆＃34; getFunctionParameters＆＃34; （在模块＆＃34; functools.js＆＃34;），因为它使用它。
/**
* Return array paraments of a function
* @param {[function]} func function
* @return {[array]} parammeters 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(' = ');
});
};
备注：
弱测试
关于它的主题资源http://www.2ality.com/2011/01/reflection-and-meta-programming-in.html
使用了ES6的功能
答案 3 :(得分：4)
var point = { x:5, y:8 };
for( var name in point ) {
// name contains the property name that you want
// point[name] contains the value
}