<!DOCTYPE html>
<html>
<head>
<title>Page Title</title>
</head>
<body>
<p>What i have</p>
<input value="1475g - 1500g" /><br>
<p>what do i need.</p>
<input style="width:50px;" value="1475" /><span>g - </span><input style="width:50px;" value="1500" /><span>g</span>
</body>
</html>Use split and replace.
const input = document.querySelector("input").value; // add an ID or class or something, this is just for demo purposes
const [ seperated1, seperated2 ] = input.replace(/g/g, "").split(" - "); // First regular expression removes all "g"s from the string. Split turns the string into an array using " - " as a delimiter
console.log(seperated1, seperated2);
Use this:
let val = '1475g - 1500g';
val = val.replace(/g| /g, '');
val = val.split('-');
console.log(val[0], val[1]);