javascript - Add propertyindex to each element in an array - Stack Overflow

admin管理员组

文章数量:1192339

I call a webservice that returns an array of objects:

$.ajax({
  dataType: "json",
  url: "WebServices/FetchMenu.aspx?P=0&L=2&mt=1",
  //data: data,
  success: function (data) {
    var foo = data;
  }
});

This is the response:

[
    {
        color: "red",
        value: "#f00"
    },
    {
        color: "green",
        value: "#0f0"
    },
    {
        color: "blue",
        value: "#00f"
    },
    {
        color: "cyan",
        value: "#0ff"
    }
]

I want add a property row_number to each element which contains the current index of the element in the array.

I need this because I am changing the order of the elements later on but want to be able to identify the original position of an element.

I call a webservice that returns an array of objects:

$.ajax({
  dataType: "json",
  url: "WebServices/FetchMenu.aspx?P=0&L=2&mt=1",
  //data: data,
  success: function (data) {
    var foo = data;
  }
});

This is the response:

[
    {
        color: "red",
        value: "#f00"
    },
    {
        color: "green",
        value: "#0f0"
    },
    {
        color: "blue",
        value: "#00f"
    },
    {
        color: "cyan",
        value: "#0ff"
    }
]

I want add a property row_number to each element which contains the current index of the element in the array.

I need this because I am changing the order of the elements later on but want to be able to identify the original position of an element.

• javascript

Share Improve this question Follow edited Sep 16, 2015 at 14:14 Felix Kling 816k180180 gold badges1.1k1.1k silver badges1.2k1.2k bronze badges asked Sep 16, 2015 at 13:30 AliAli 3,46966 gold badges4343 silver badges5656 bronze badges 7

• What you mean by row number? You have result set and you want to add additional property to each single row? – Kristian Vitozev Commented Sep 16, 2015 at 13:35
• becuase i run the code in my page that foo .push(foo .shift()); it change the order of json varible and i want to know witch elemnt is 1st in foo – Ali Commented Sep 16, 2015 at 13:36
• Can you provide an example of the data and your expected result? What have you tried so far? – Felix Kling Commented Sep 16, 2015 at 13:38
• @Felix Kling : its a simple json varible ...the main question is if i shift and then push some elment in foo, the order of array is change and after run that code the element that was 1st in foo is now last elemnt in foo – Ali Commented Sep 16, 2015 at 13:43
• So you don't want to add a property to foo but to all objects in foo? Or just to the first one? An example would clarify a lot. – Felix Kling Commented Sep 16, 2015 at 13:45

 |  Show 2 more comments

4 Answers 4

Sorted by: Reset to default 12

There is nothing really special to do. Simply iterate over the array and add the property to each element:

for (var i = 0; i < foo.length; i++) {
  foo[i].row_number = i;
}

// or with forEach

foo.forEach(function(row, index) {
  row.row_number = index;
});

See Access / process (nested) objects, arrays or JSON for more general information about nested data structures in JavaScript.

You could also use map in case you want to keep the old object around, or wanted to do it in a call chain not modifying an existing array.

const oldArray = [{a: 'Andy'}, {b: 'Betty'}, {c: 'Charlie'}];
const newArray = oldArray.map((item, index) => ({index, ...item}));
console.log(newArray);
// Array [Object { index: 0, a: "Andy" }, Object { index: 1, b: "Betty" }, Object { index: 2, c: "Charlie" }]

If foo is one object you can do

foo.Row_Number

if is list you can use $.each and do the same for each object.

$.each(obj, function (index) {
    this.row_number = index + 1;
});

let index = 0;
items.forEach((item) => (item.index = index++));

本文标签： javascriptAdd propertyindex to each element in an arrayStack Overflow