如何在JavaScript中迭代对象？

Question

我有这个对象。我想在JavaScript中迭代这个对象。这怎么可能？

var dictionary = {
    "data": [
        {"id":"0","name":"ABC"},
        {"id":"1","name":"DEF"}
    ],
    "images": [
        {"id":"0","name":"PQR"},
        {"id":"1","name":"xyz"}
    ]
};

Answer 1

您可以使用以下代码执行此操作。首先使用dictionary.data获取数据数组并将其分配给数据变量。之后，您可以使用普通for循环迭代它。每行都是数组中的行对象。

var data = dictionary.data;

for (var i in data)
{
     var id = data[i].id;
     var name = data[i].name;
}

您可以按照类似的方法迭代图像数组。

Answer 2

也有这种方式（EcmaScript5的新功能）：

dictionary.data.forEach(function(item){
    console.log(item.name + ' ' + item.id);
});

图像的方法相同

Answer 3

类似的东西：

var dictionary = {"data":[{"id":"0","name":"ABC"},{"id":"1", "name":"DEF"}], "images": [{"id":"0","name":"PQR"},{"id":"1","name":"xyz"}]};

for (item in dictionary) {
  for (subItem in dictionary[item]) {
     console.log(dictionary[item][subItem].id);
     console.log(dictionary[item][subItem].name);
  }
}

Answer 4

使用点表示法和/或括号表示法访问对象属性，使用for loops迭代数组：

var d, i;

for (i = 0; i < dictionary.data.length; i++) {
  d = dictionary.data[i];
  alert(d.id + ' ' + d.name);
}

您还可以使用for..in循环迭代数组;但是，添加到Array.prototype的属性可能会显示出来，您可能不一定按正确的顺序获取数组元素，甚至也不一定按照任何一致的顺序。

Answer 5

for(index in dictionary) {
 for(var index in dictionary[]){
    // do something
  }
}

Answer 6

使用生成器函数，您可以迭代深度键值。

function * deepEntries(obj) { 
    for(let [key, value] of Object.entries(obj)) {
        if (typeof value !== 'object') 
            yield [key, value]
        else 
            for(let entries of deepEntries(value))
                yield [key, ...entries]
    }
}

const dictionary = {
    "data": [
        {"id":"0","name":"ABC"},
        {"id":"1","name":"DEF"}
    ],
    "images": [
        {"id":"0","name":"PQR"},
        {"id":"1","name":"xyz"}
    ]
}

for(let entries of deepEntries(dictionary)) {
    const key = entries.slice(0, -1).join('.')
    const value = entries[entries.length-1]
    console.log(key, value)
}

Answer 7

var dictionary = {
        "data":[{"id":"0","name":"ABC"}, {"id":"1","name":"DEF"}],
        "images": [ {"id":"0","name":"PQR"},"id":"1","name":"xyz"}]
};


for (var key in dictionary) {
    var getKey = dictionary[key];
    getKey.forEach(function(item) {
        console.log(item.name + ' ' + item.id);
    });
}

Answer 8

使用for和foreach循环

var dictionary = {
     data: [{ id: "0", name: "ABC" }, { id: "1", name: "DEF" }],
     images: [{ id: "0", name: "PQR" }, { id: "1", name: "xyz" }]
};
dictionary.data.forEach(item => {
     console.log(item.id + " " + item.name);
});

for (var i = 0; i < dictionary.data.length; i++) {
     console.log(dictionary.data[i].id + " " + dictionary.data[i].name);
}

Answer 9

这是您拥有的所有选项：

1。 for...of（ES2015）

var dictionary = {
    "data": [
        {"id":"0","name":"ABC"},
        {"id":"1","name":"DEF"}
    ],
    "images": [
        {"id":"0","name":"PQR"},
        {"id":"1","name":"xyz"}
    ]
};

for (const entry of dictionary.data) {
  console.log(JSON.stringify(entry))
}

2。 Array.prototype.forEach（ES5）

var dictionary = {
    "data": [
        {"id":"0","name":"ABC"},
        {"id":"1","name":"DEF"}
    ],
    "images": [
        {"id":"0","name":"PQR"},
        {"id":"1","name":"xyz"}
    ]
};

dictionary.data.forEach(function(entry) {
  console.log(JSON.stringify(entry))
})

3。 for()（ES1）

var dictionary = {
    "data": [
        {"id":"0","name":"ABC"},
        {"id":"1","name":"DEF"}
    ],
    "images": [
        {"id":"0","name":"PQR"},
        {"id":"1","name":"xyz"}
    ]
};

for (let i = 0; i < dictionary.data.length; i++) {
  console.log(JSON.stringify(dictionary.data[i]))
}