Javascript 如何在javascript中动态地向对象数组添加值？
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how to add values to an array of objects dynamically in javascript?
提问by Mujtaba Haider
this is an array of objects,
这是一个对象数组，
var data = [
{"label" : "1", "value" : 12},
{"label" : "1", "value" : 12},
{"label" : "1", "value" : 12},
{"label" : "1", "value" : 12}
];
how can i add values to these dynamically? i tried the below code but no success
我如何动态地向这些添加值？我尝试了下面的代码但没有成功
var lab =["1","2","3", "4"];
var val = [42,55,51,22];
var data = new Array();
for(var i=0; i<4; i++){
data[i].label = lab[i];
data[i].value = val[i];
}
anyone please.. thanks in advance
任何人请..提前致谢
回答by Felix Kling
You have to instantiate the object first. The simplest way is:
您必须先实例化对象。最简单的方法是：
var lab =["1","2","3"];
var val = [42,55,51,22];
var data = [];
for(var i=0; i<4; i++) {
data.push({label: lab[i], value: val[i]});
}
Or an other, less concise way, but closer to your original code:
或者另一种不太简洁但更接近原始代码的方式：
for(var i=0; i<4; i++) {
data[i] = {}; // creates a new object
data[i].label = lab[i];
data[i].value = val[i];
}
array()will not create a new array (unless you defined that function). Either Array()or new Array()or just [].
array()不会创建新数组（除非您定义了该函数）。无论是Array()或new Array()，或只是[]。
I recommend to read the MDN JavaScript Guide.
我建议阅读MDN JavaScript 指南。
回答by its4zahoor
In Year 2019, we can use Javascript's ES6Spread syntaxto do it concisely and efficiently
2019年我们可以使用Javascript的ES6 Spread语法简洁高效
data = [...data, {"label": 2, "value": 13}]
Examples
例子
var data = [
{"label" : "1", "value" : 12},
{"label" : "1", "value" : 12},
{"label" : "1", "value" : 12},
];
data = [...data, {"label" : "2", "value" : 14}]
console.log(data)For your case (i know it was in 2011), we can do it with map()& forEach()like below
对于您的情况（我知道是在 2011 年），我们可以使用map()和forEach() 来完成，如下所示
var lab = ["1","2","3","4"];
var val = [42,55,51,22];
//Using forEach()
var data = [];
val.forEach((v,i) =>
data= [...data, {"label": lab[i], "value":v}]
)
//Using map()
var dataMap = val.map((v,i) =>
({"label": lab[i], "value":v})
)
console.log('data: ', data);
console.log('dataMap : ', dataMap);