在不替换子项的情况下添加到Javascript对象

Question

I am trying to run a for loop to create new javascript objects and add to an existing javascript object without replacing.

For example I am trying to create this as the output without the group[i] being overwritten every time ( and just adding the number[i] data ):

{
    "group1": {
        "number1": "data",
        "number2": "data",
        "number3": "data"
    },
    "group2": {
        "number1": "data",
        "number2": "data"
    }
}

My loop looks like this:

var array = [{
    "groupName": "group1",
    "number": "number1",
    "data": "data"
}, {
    "groupName": "group1",
    "number": "number2",
    "data": "data"
}, {
    "groupName": "group1",
    "number": "number3",
    "data": "data"
}, {
    "groupName": "group2",
    "number": "number1",
    "data": "data"
}, {
    "groupName": "group2",
    "number": "number2",
    "data": "data"
}]

var groupLinks = {};

for(i = 0; i < array.length; i++) {

    groupLinks[array[i].groupName] = { 
        [array[i].number]: array[i].data

}

As you can see with this code, my loop is only going to replace "group1" and "group2" every time.

Answer 1

This is how I would go about approaching this:

 var array = [{ "groupName": "group1", "number": "number1", "data": "data" }, { "groupName": "group1", "number": "number2", "data": "data" }, { "groupName": "group1", "number": "number3", "data": "data" }, { "groupName": "group2", "number": "number1", "data": "data" }, { "groupName": "group2", "number": "number2", "data": "data" }]; var groupLinks = {}; array.forEach( function (element) { var groupName = element.groupName; (groupLinks[groupName] = groupLinks[groupName] || {}) [element.number] = element.data; } ); console.log(groupLinks); 

here I used the || operator to create a new group when none was present, overwriting the existing groupLinks[groupName] at each iteration, and I used a forEach construct to loop over array elements.

Answer 2

Try this:

    var array = [{
        "groupName": "group1",
        "number": "number1",
        "data": "data"
    }, {
        "groupName": "group1",
        "number": "number2",
        "data": "data"
    }, {
        "groupName": "group1",
        "number": "number3",
        "data": "data"
    }, {
        "groupName": "group2",
        "number": "number1",
        "data": "data"
    }, {
        "groupName": "group2",
        "number": "number2",
        "data": "data"
    }]

    var groupLinks = {};

    array.forEach(function(el){
       if(groupLinks[el.groupName]){
         groupLinks[el.groupName][el.number] = el.data
       }
       else{
         groupLinks[el.groupName] = {};
         groupLinks[el.groupName][el.number] = el.data
       }

    });

   console.log(groupLinks);

Answer 3

If you're not afraid of a little ES2015, this reduce job should work for you

 let array = [{"groupName":"group1","number":"number1","data":"data"},{"groupName":"group1","number":"number2","data":"data"},{"groupName":"group1","number":"number3","data":"data"},{"groupName":"group2","number":"number1","data":"data"},{"groupName":"group2","number":"number2","data":"data"}]; let groupLinks = array.reduce((gl, group) => { gl[group.groupName] = Object.assign({ [group.number]: group.data }, gl[group.groupName]); return gl; }, Object.create(null)); console.log(groupLinks); 

Answer 4

Please try this:

    var groupLinks = {};

    for(i = 0; i < array.length; i++) {
       var groupLinks2 = groupLinks[array[i].groupName];
       if(!groupLinks2){
           groupLinks2 ={};
           var a = array[i].number;
           groupLinks2[a] = array[i].data;
      }else{
         var a = array[i].number;
        groupLinks2[a] = array[i].data;
      }
      groupLinks[array[i].groupName] = groupLinks2;

   }