如何在Javascript中合并数组？

Question

I have built my array as following.

var myArray = [];
for(var i = 0; i < data.length; i++)
{
    var product = data[i][0];
    var size = data[i][1];
    myArray.push({product:product, value:size})
}

How the data has been constructed is out of the scope. When I loop through myArray I get the following result in the console.log.

for(var i = 0; i < myArray.length; i++)
{
    var product = myArray[i].product;
    var size = myArray[i].value;
    console.log(product + ' => ' + size);
}

Shoe A => S
Shoe A => M
Shoe B => XS
Shoe B => S
Shoe B => M
Shoe C => M
Shoe C => LG
Shoe D => S
Shoe D => M
Shoe D => LG
Shoe D => XL

How should I do to get the following result?

Shoe A => [S, M]
Shoe B => [XS, S, M]
Shoe C => [M, LG]
Shoe D => [S, M, LG, XL]

I tend to post myArray to a PHP handler using AJAX.

Answer 1

To get desired output in single loop:

Shoe A => [S, M]

Shoe B => [XS, S, M]

Shoe C => [M, LG]

Shoe D => [S, M, LG, XL]

You can try this solution. Use hash instead of array.

var myArray = {};

for(var i = 0; i < data.length; i++)
{
    var product = data[i][0];
    var size = data[i][1];
    if(myArray[product] === undefined) {
       myArray[product] = []
    }
    myArray[product].push(size)
}

Answer 2

You should be able to use Array.reduce() to add each value to a new Object :

[
  {product:'shoe a', value:'L'},
  {product:'shoe b', value:'M'},
  {product:'shoe b', value:'S'}

].reduce(function(memo, item) {
  var arr = memo[item.product] || [];
  arr.push(item.value);
  memo[item.product] = arr;
  return memo
}, {})

Answer 3

I think you want to build a structure like this:

var oData = {
  A : [Some Sizes],
  B : [Some Sizes] ...
}

where A and B are your products. So when you loop over your initial data you need to:

var sSize = "size you want to add";
    if(oData[A] === undefined){
       oData.A = [sSize];
    }else{
       oData[A].push(sSize);
    }

Answer 4

your output array list should have object like this { name:"productName",size: [{ "productSize"}]

look example, aaa is output array

    var aaa = [];
        var names = [];

      for(var i = 0; i < myArray.length; i++)
        {
                if(names.indexOf(myArray[i].product)>-1){
                        for(var j=0; j< aaa.length; j++){
                            if(aaa[j].name == myArray[i].product){
                               aaa[j].size.push(myArray[i].value)
                             }
                     }
            }
            else{
                var ppp = {};
                ppp.name = "";
                ppp.size = [];
                ppp.name =  myArray[i].product;
                ppp.size.push(myArray[i].value);
                names.push(ppp.name);
                aaa.push(ppp);
            }
        }

        for(var i=0; i<aaa.length; i++ ){
        console.log(aaa[i]);
        }