JSFiddle - React, Tailwind, and code Playground

JavaScript

function formatNum(num) {
    return ('0000'+num.toFixed(2)).slice(-7);
}

var cases = [0, 9.8, 0.008, 98765, 12.34567, 9999.999, 37549.18598];

for (var i=0; i<cases.length; i++) {
    var n = cases[i];
    console.log(n+' = '+formatNum(n));
    document.writeln(n+' = '+formatNum(n)+'<br>');
}