JSFiddle - React, Tailwind, and code Playground

JavaScript

var size = 7;
var half = Math.floor(size / 2);
var txt = '';
for (var i = 0; i < size; i++) {
    for (var j = 0; j < size; j++) {
        var char = '0';
        if (i + j < half) { 
            char = '1';
        } 
        if (j - i > half) {
            char = '2';
        } 
        if (i - j > half) {
           char = '3';
        } 
        if (i + j > size + half - 1) {
            char = '4';
        }
        txt += char;
    
    }    
    txt += '<br>'
}
document.body.innerHTML = txt;