如何在javascript中向数组添加新对象（键值对）？

Question

I have an array as :

items=[{'id':1},{'id':2},{'id':3},{'id':4}];

How should I add a new pair {'id':5} to the array?

Answer 1

使用.push ：

items.push({'id':5});

Answer 2

.push() will add elements to the end of an array.

Use .unshift() if need to add some element to the beginning of array ie:

items.unshift({'id':5});

Demo:

 items = [{'id': 1}, {'id': 2}, {'id': 3}, {'id': 4}]; items.unshift({'id': 0}); console.log(items);

And use .splice() in case you want to add object at a particular index ie:

items.splice(2, 0, {'id':5});
           // ^ Given object will be placed at index 2...

Demo:

 items = [{'id': 1}, {'id': 2}, {'id': 3}, {'id': 4}]; items.splice(2, 0, {'id': 2.5}); console.log(items);

Answer 3

Sometimes .concat() is better than .push() since .concat() returns the new array whereas .push() returns the length of the array.

Therefore, if you are setting a variable equal to the result, use .concat() .

items = [{'id': 1}, {'id': 2}, {'id': 3}, {'id': 4}];
newArray = items.push({'id':5})

In this case, newArray will return 5 (the length of the array).

newArray = items.concat({'id': 5})

However, here newArray will return [{'id': 1}, {'id': 2}, {'id': 3}, {'id': 4}, {'id': 5}].

Answer 4

New solution with ES6

Default object

object = [{'id': 1}, {'id': 2}, {'id': 3}, {'id': 4}];

Another object

object =  {'id': 5};

Object assign ES6

resultObject = {...obj, ...newobj};

Result

[{'id': 1}, {'id': 2}, {'id': 3}, {'id': 4}, {'id': 5}];

Answer 5

If you're doing jQuery, and you've got a serializeArray thing going on concerning your form data, such as :

var postData = $('#yourform').serializeArray();

// postData (array with objects) : 
// [{name: "firstname", value: "John"}, {name: "lastname", value: "Doe"}, etc]

...and you need to add a key/value to this array with the same structure, for instance when posting to a PHP ajax request then this :

postData.push({"name": "phone", "value": "1234-123456"});

Result:

// postData : 
// [{name: "firstname", value: "John"}, {name: "lastname", value: "Doe"}, {"name":"phone","value":"1234-123456"}]