JSFiddle - React, Tailwind, and code Playground

JavaScript

var mainObj = {
    "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"
    }
};
var result = {};

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

alert(JSON.stringify(result));