Javascript 迭代对象的值
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Iterate over values of object
提问by Matthias M
I want to iterate over all values of a map. I know it's possible to iterate over all keys. But is it possible to iterate directly over the values?
我想遍历地图的所有值。我知道可以遍历所有键。但是是否可以直接迭代这些值？
var map = { key1 : 'value1', key2 : 'value2' }
for (var key in map) { ...} // iterates over keys
回答by André Chalella
It's not a map. It's simply an Object.
这不是地图。它只是一个Object.
Edit:below code is worse than OP's, as Amit pointed out in comments.
编辑：正如 Amit 在评论中指出的那样，下面的代码比 OP 更糟糕。
You can "iterate over the values" by actually iterating over the keyswith:
您可以通过实际迭代键来“迭代值” ：
var value;
Object.keys(map).forEach(function(key) {
value = map[key];
console.log(value);
});
回答by Parag Jadhav
I iterate like this and it works for me.
我像这样迭代，它对我有用。
for (let [k, v] of myMap) {
console.log("Key: " + k);
console.log("Value: " + v);
}
Hope this helps :)
希望这可以帮助 ：）
回答by Ben Aston
In the sense I think you intended, in ES5 or ES2015, no, not without some work on your part.
从某种意义上说，我认为在 ES5 或 ES2015 中，不，不是没有你的一些工作。
In ES2016, probably with object.values.
在 ES2016 中，可能使用object.values.
Mind you Arrays in JavaScript are effectively a map from an integer to a value, and the values in JavaScript arrays can be enumerated directly.
请注意 JavaScript 中的数组实际上是从整数到值的映射，并且可以直接枚举 JavaScript 数组中的值。
['foo', 'bar'].forEach(v => console.log(v)); // foo bar
Also, in ES2015, you can make an object iterable by placing a function on a property with the name of Symbol.iterator:
此外，在 ES2015 中，您可以通过将函数放置在名称为 的属性上来使对象可迭代Symbol.iterator：
var obj = {
foo: '1',
bar: '2',
bam: '3',
bat: '4',
};
obj[Symbol.iterator] = iter.bind(null, obj);
function* iter(o) {
var keys = Object.keys(o);
for (var i=0; i<keys.length; i++) {
yield o[keys[i]];
}
}
for(var v of obj) { console.log(v); } // '1', '2', '3', '4'
Also, per other answers, there are other built-ins that provide the functionality you want, like Map(but notWeakMapbecause it is not iterable) and Setfor example (but these are not present in all browsers yet).
此外，根据其他答案，还有其他内置程序可以提供您想要的功能，例如Map（但不是WeakMap因为它不可迭代）和Set例如（但这些尚未出现在所有浏览器中）。
回答by dmigo
EcmaScript 2017 introduced Object.entriesthat allows you to iterate over values and keys. Documentation
引入的 EcmaScript 2017Object.entries允许您迭代值和键。文档
var map = { key1 : 'value1', key2 : 'value2' }
for (let [key, value] of Object.entries(map)) {
console.log(`${key}: ${value}`);
}
The result will be:
结果将是：
key1: value1
key2: value2
键 1
：值1 键2：值 2
回答by Menelaos Kotsollaris
In case you want to deeply iterateinto a complex (nested) object for each key & value, you can do so using Object.keys():
如果您想为每个key & value深度迭代到一个复杂的（嵌套）对象，您可以使用Object.keys()：
const iterate = (obj) => {
Object.keys(obj).forEach(key => {
console.log(`key: ${key}, value: ${obj[key]}`)
if (typeof obj[key] === 'object') {
iterate(obj[key])
}
})
}
回答by Amit
回答by dpr
You could use underscore.js and the each function:
您可以使用underscore.js 和 each 函数：
_.each({key1: "value1", key2: "value2"}, function(value) {
console.log(value);
});
