扩展加比·普卡鲁的答案，包括对第2个问题的回答。

a = new Array();
b = new Object();
a[0] = b;

var c = a[0]; // c is now the object we inserted into a...

a=[];
a.push(['b','c','d','e','f']);

性能

今天2020.12.04，我在Chrome v86、Safari v13.1.2和Firefox v83上对所选解决方案的MacOs HighSierra 10.13.6上执行测试。

结果

适用于所有浏览器

基于长度的就地解决方案(B)对于小数组是最快的，在Firefox中也适用于大数组，对于Chrome和Safari也很快 基于push (A)的in-place解决方案对于Chrome和Safari上的大数组速度最快，对于Firefox和小数组速度最快 就地解决方案C对于大数组慢，对于小数组中快 非原位解D和E对于大数组是很慢的 非就地解决方案E、F和D(在Firefox上)对于小型数组来说速度较慢

细节

我执行2个测试用例:

对于10个元素的小数组-你可以在这里运行它 对于有1M个元素的大数组-你可以在这里运行它

下面的代码片段展示了解决方案之间的差异 一个, B, C, D, E, F

PS:答案B被删除了——但实际上它是第一个使用这种技术的答案，所以如果你有机会看到它，请点击“取消删除”。

// https://stackoverflow.com/a/6254088/860099 function A(a,o) { a.push(o); return a; } // https://stackoverflow.com/a/47506893/860099 function B(a,o) { a[a.length] = o; return a; } // https://stackoverflow.com/a/6254088/860099 function C(a,o) { return a.concat(o); } // https://stackoverflow.com/a/50933891/860099 function D(a,o) { return [...a,o]; } // https://stackoverflow.com/a/42428064/860099 function E(a,o) { const frozenObj = Object.freeze(o); return Object.freeze(a.concat(frozenObj)); } // https://stackoverflow.com/a/6254088/860099 function F(a,o) { a.unshift(o); return a; } // ------- // TEST // ------- [A,B,C,D,E,F].map(f=> { console.log(`${f.name} ${JSON.stringify(f([1,2],{}))}`) }) <script src="https://code.jquery.com/jquery-3.5.1.min.js" integrity="sha256-9/aliU8dGd2tb6OSsuzixeV4y/faTqgFtohetphbbj0=" crossorigin="anonymous"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.20/lodash.min.js" integrity="sha512-90vH1Z83AJY9DmlWa8WkjkV79yfS2n2Oxhsi2dZbIv0nC4E6m5AbH8Nh156kkM7JePmqD6tcZsfad1ueoaovww==" crossorigin="anonymous"> </script> This shippet only presents functions used in performance tests - it not perform tests itself!

这里是chrome的示例结果

使用array .push()将任何东西放入数组。

var a=[], b={};
a.push(b);    
// a[0] === b;

关于数组的额外信息

一次添加多个项目

var x = ['a'];
x.push('b', 'c');
// x = ['a', 'b', 'c']

将项添加到数组的开头

var x = ['c', 'd'];
x.unshift('a', 'b');
// x = ['a', 'b', 'c', 'd']

将一个数组的内容添加到另一个数组中

var x = ['a', 'b', 'c'];
var y = ['d', 'e', 'f'];
x.push.apply(x, y);
// x = ['a', 'b', 'c', 'd', 'e', 'f']
// y = ['d', 'e', 'f']  (remains unchanged)

从两个数组的内容创建一个新数组

var x = ['a', 'b', 'c'];
var y = ['d', 'e', 'f'];
var z = x.concat(y);
// x = ['a', 'b', 'c']  (remains unchanged)
// y = ['d', 'e', 'f']  (remains unchanged)
// z = ['a', 'b', 'c', 'd', 'e', 'f']

JavaScript is case-sensitive. Calling new array() and new object() will throw a ReferenceError since they don't exist. It's better to avoid new Array() due to its error-prone behavior. Instead, assign the new array with = [val1, val2, val_n]. For objects, use = {}. There are many ways when it comes to extending an array (as shown in John's answer) but the safest way would be just to use concat instead of push. concat returns a new array, leaving the original array untouched. push mutates the calling array which should be avoided, especially if the array is globally defined. It's also a good practice to freeze the object as well as the new array in order to avoid unintended mutations. A frozen object is neither mutable nor extensible (shallowly).

应用这些观点并回答你的两个问题，你可以定义一个这样的函数:

function appendObjTo(thatArray, newObj) {
  const frozenObj = Object.freeze(newObj);
  return Object.freeze(thatArray.concat(frozenObj));
}

用法:

// Given
const myArray = ["A", "B"];
// "save it to a variable"
const newArray = appendObjTo(myArray, {hello: "world!"});
// returns: ["A", "B", {hello: "world!"}]. myArray did not change.

使用push，你甚至可以向数组中添加多个对象

  let myArray = [];

   myArray.push(
              {name:"James", dataType:TYPES.VarChar, Value: body.Name},
              {name:"Boo", dataType:TYPES.VarChar, Value: body.Name},
              {name:"Alina", dataType:TYPES.VarChar, Value: body.Name}
             );