JSFiddle - React, Tailwind, and code Playground

JavaScript

Array.prototype.indexOf = function(elem) {
    for (var i = 0; i < this.length; i++){
        if (this[i].id === elem)
            return i;
    }
    return -1;
}

var arrayName = [
{id: "a", gender: "man",   item: "stuff"},
{id: "b", gender: "woman", item: "stuff"},
{id: "c", gender: "man",   item: "stuff"},
{id: "d", gender: "man",   item: "stuff"}
];
alert(arrayName.indexOf("b"));