JSFiddle - React, Tailwind, and code Playground

JavaScript

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