JSFiddle - React, Tailwind, and code Playground

HTML

<div id='before'></div>
<div id="after"></div>

JavaScript

let listObjects = [ {param:1} , {param:2} , {param:3} ]
document.getElementById("before").innerHTML =JSON.stringify(listObjects)
let newArray = []
listObjects.map(
	(el,ind)=>{
  	if (ind === 0){
    	newArray.push({param:999999})
    }
    else
    {
    	newArray.push(el)
    }
  }
)

document.getElementById("after").innerHTML =JSON.stringify(newArray)