Javascript add properties with the same name to an object

问题

    var elements = document.getElementsByClassName("someClass");
    var obj = {};
    for (var i = 0; i < elements.length; i++){
        obj.userId = elements[i].id 
    } 

// output: obj = {userId: 1, userId: 2, userId: 3.....etc}

Is it possible in some way? Thanks.

回答1:

keys in Object must be unique, you can try use Array, like this

var obj = [];
var data = {};
for (var i = 0; i < elements.length; i++) {
   data = {
     userId: elements[i].id 
   };
   obj.push(data);
} 

// [ {userId: 1}, {userId: 2} ... ] 

回答2:

The JSON RFC says "the names within an object SHOULD be unique" - see here for more info however should your object have a duplicate key the last occurrence will be used.

An array would be a better solution for your data.

来源：https://stackoverflow.com/questions/34175975/javascript-add-properties-with-the-same-name-to-an-object