How can i separate the second set from this object?

Question

I've an javascript map in which i would like to separate the last set of objects,

{
    "97483": {
        "_index": 0,
        "text_html": "sadf"
    },
    "97484": {
        "_index": 1,
        "text_html": "sfhsdfasdfsdf"
    },
    "97485": {
        "_index": 2,
        "text_html": "test1"
    },
    "97486": {
        "_index": 3,
        "text_html": "test2"
    },
    "97487": {
        "_index": 4,
        "text_html": "test3"
    },
    "97493": {
        "_index": 0,
        "text_html": "test9"
    },
    "97494": {
        "_index": 1,
        "text_html": "test10"
    },
    "97495": {
        "_index": 2,
        "text_html": "test11"
    },
    "97496": {
        "_index": 3,
        "text_html": "test11"
    },
    "97893": {
        "_index": 0,
        "text_html": "test99"
    },
    "97894": {
        "_index": 1,
        "text_html": "test999"
    },
    "97895": {
        "_index": 2,
        "text_html": "test9999"
    },

}

In this javascript map how i can separate out the

"97893": {
        "_index": 0,
        "text_html": "test99"
    },
    "97894": {
        "_index": 1,
        "text_html": "test999"
    },
    "97895": {
        "_index": 2,
        "text_html": "test9999"
    },

Actually the main motive is to separate out the last set of elements whose _index starts from 0. Any help would be greatly appreciated.

please define last in an object, which properties have no order? — Nina Scholz, May 09 '16 at 09:29
@Nina, actually they have in ES6 (order of insertion is preserved IIRC). This question is still too broad, though. — Frédéric Hamidi, May 09 '16 at 09:30
Describe the logic that makes something part of the second set you want. — Shilly, May 09 '16 at 09:32
@FrédéricHamidi Not in all cases I don't think? I don't think `for..in` has a defined order. https://esdiscuss.org/topic/property-ordering-of-enumerate-getownpropertynames — CodingIntrigue, May 09 '16 at 09:47
@RGraham, [you're right](http://stackoverflow.com/q/30076219/464709). We're only halfway there apparently. — Frédéric Hamidi, May 09 '16 at 09:51

score 0 · Answer 1 · answered May 09 '16 at 09:33

Try to write your code like,

var mainObj = {...}; //your object
var result = {};

Object.keys(mainObj).forEach(function(itm){
 if(mainObj[itm]._index == 0) result = {};
 result[itm] = mainObj[itm];
});

The above code will collect the last set of objects from the main object.

DEMO

score 0 · Answer 2 · answered May 09 '16 at 10:04

A proposal for unordered properties.

var object = { "97483": { "_index": 0, "text_html": "sadf" }, "97484": { "_index": 1, "text_html": "sfhsdfasdfsdf" }, "97485": { "_index": 2, "text_html": "test1" }, "97486": { "_index": 3, "text_html": "test2" }, "97487": { "_index": 4, "text_html": "test3" }, "97493": { "_index": 0, "text_html": "test9" }, "97494": { "_index": 1, "text_html": "test10" }, "97495": { "_index": 2, "text_html": "test11" }, "97496": { "_index": 3, "text_html": "test11" }, "97893": { "_index": 0, "text_html": "test99" }, "97894": { "_index": 1, "text_html": "test999" }, "97895": { "_index": 2, "text_html": "test9999" } },
    keys = Object.keys(object).map(Number).sort((a, b) => a - b),
    key = keys.filter(a => object[a]._index === 0),
    result = {};

keys.forEach(function (a) {
    if (a >= this) {
        result[a] = object[a];
    }
}, key[key.length - 1]);

document.write('<pre>' + JSON.stringify(result, 0, 4) + '</pre>');

Redu · Answer 3 · 2016-05-10T00:02:10.507

Can be done with pure JS in an assignment instruction.

var dataObj = { "97483": { "_index": 0, "text_html": "sadf" }, "97484": { "_index": 1, "text_html": "sfhsdfasdfsdf" }, "97485": { "_index": 2, "text_html": "test1" }, "97486": { "_index": 3, "text_html": "test2" }, "97487": { "_index": 4, "text_html": "test3" }, "97493": { "_index": 0, "text_html": "test9" }, "97494": { "_index": 1, "text_html": "test10" }, "97495": { "_index": 2, "text_html": "test11" }, "97496": { "_index": 3, "text_html": "test11" }, "97893": { "_index": 0, "text_html": "test99" }, "97894": { "_index": 1, "text_html": "test999" }, "97895": { "_index": 2, "text_html": "test9999" } },
         ok = Object.keys(dataObj),
    reduced = ok.fill(false,0,ok.reduce((p,c) => (p.push(dataObj[c]._index),p),[]).lastIndexOf(0)).reduce((p,c) => (c && (p[c] = dataObj[c]),p),{});

document.write("<pre>" + JSON.stringify(reduced,null,2) + "</pre>");

How can i separate the second set from this object?

3 Answers3

DEMO