JSFiddle - React, Tailwind, and code Playground

by gaby de wilde

JavaScript

nums = new Set(['.','1','2','3','4','5','6','7','8','9','0']);
    hasOnlyNumbers=str=>str.split('.').length<3&&[...str[0]=='-'?str.substring(1):str].every(x=>nums.has(x));

    alert(hasOnlyNumbers('-3243.234332'));
    alert(hasOnlyNumbers('-3243.234.3.32'));