add array object with JavaScript

Question

May be it is dumb question. I have array object like

var projects = [
        {
            value: "jquery",
            label: "jQuery",
            desc: "the write less, do more, JavaScript library",
            icon: "jquery_32x32.png"
        },
        {
            value: "jquery-ui",
            label: "jQuery UI",
            desc: "the official user interface library for jQuery",
            icon: "jqueryui_32x32.png"
        },
        {
            value: "sizzlejs",
            label: "Sizzle JS",
            desc: "a pure-JavaScript CSS selector engine",
            icon: "sizzlejs_32x32.png"
        }
    ];

length of 3

I want to add id in all objects like

        {
            id:1
            value: "jquery",
            label: "jQuery",
            desc: "the write less, do more, JavaScript library",
            icon: "jquery_32x32.png"
        },
        {
            id:2
            value: "jquery-ui",
            label: "jQuery UI",
            desc: "the official user interface library for jQuery",
            icon: "jqueryui_32x32.png"
        },
        {
            id:3
            value: "sizzlejs",
            label: "Sizzle JS",
            desc: "a pure-JavaScript CSS selector engine",
            icon: "sizzlejs_32x32.png"
        }

How can i do that?

Rajaprabhu Aravindasamy · Accepted Answer · 2016-03-29 18:01:19Z

3

You can do it by using Array.prototype.map(),

projects = projects.map(function(itm,i){
 return (itm.id = i+1, itm);
});

DEMO

If you don't want to use functional programming, then you can use a simple for loop for this purpose no need for "forEach",

for(var i=0,len=projects.length; i<len; i++){
  projects[i].id = i+1;
}

edited Mar 29, 2016 at 18:01

answered Mar 29, 2016 at 17:52

Rajaprabhu Aravindasamy

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2 Comments

Emissary Over a year ago

It's a bit odd cloning the array for no reason, in a way that mutates the original objects anyway.

Rajaprabhu Aravindasamy Over a year ago

@Emissary Let OP know about that(map) also. It would be handy for him in other occasions. Also I have provided a solution for the problem that you are saying by a simple for loop.

Nina Scholz · Accepted Answer · 2016-03-29 18:00:39Z

2

No need for Array#map, because the access is direct possible with itm as object.

projects.forEach(function(itm, i) {
   itm.id = i + 1;
});

edited Mar 29, 2016 at 18:00

answered Mar 29, 2016 at 17:54

Nina Scholz

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1 Comment

RomanPerekhrest Over a year ago

but forEach method doesn't return anything

RomanPerekhrest · Accepted Answer · 2016-03-29 18:08:33Z

0

If care about speed ) ... "fast" solution with "negative" while loop:

var len = projects.length;
while (len--) {
    projects[len]['id'] = len + 1;
}

answered Mar 29, 2016 at 18:08

RomanPerekhrest

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