JSFiddle - React, Tailwind, and code Playground

HTML

<table border="1" id="keret"></table>

JavaScript

function matrix() {
    var e = prompt("Cols?", 0);
    var f = prompt("Rows?", 0);
    
    var matrix = [];
    for (var i = 0; i < e; i++) {
        matrix[i] = [];
        for (var j = 0; j < f; j++) {
            matrix[i][j] = Math.floor((Math.random() * 1000) + 1);
        }
    }
    for (var i = 0; i < e; i++) {
        var row = document.createElement("tr"); 
        for (var j = 0; j < f; j++) {
            var cell = document.createElement("td");
            cell.innerHTML = matrix[i][j];
            row.appendChild(cell);
        }
        document.getElementById("keret").appendChild(row);
    }
}

matrix();