JSFiddle - React, Tailwind, and code Playground

JavaScript

var a = new Array(); 
a.push({"1": "apple", "2": "banana"}); 
a.push({"3": "coconut", "4": "mango"});

GetIndexByValue(a, "coconut");

function GetIndexByValue(arrayName, value) {  
var keyName = "";
var index = -1;
for (var i = 0; i < arrayName.length; i++) { 
   var obj = arrayName[i]; 
        for (var key in obj) {          
            if (obj[key] == value) { 
                keyName = key; 
                index = i;
            } 
        } 
    }
    //console.log(index); 
    return index;
}