JSFiddle - React, Tailwind, and code Playground

HTML

<input id="input" value="25 million, 23 thousand, 943"></input>
<button id="convert">Convert</button>
<div id="result"></div>

JavaScript

var UNIT_SEPARATOR = ', '; // what separates the number parts (millions from thousands, ecc)
var VALUE_UNIT_SEPARATOR = ' '; // what goes between the value and the unit
var unitMap = {
    billion:9,
    million:6,
    thousand:3,
    '':0
}; // add as many units as you like

$('#convert').click(function () {
    var number = $('#input').val();
    var numberParts = number.split(UNIT_SEPARATOR);
    var convertedNumber = 0;
    
    for (var i = 0; i < numberParts.length; i++) {
        var splitUnit = numberParts[i].split(' ');
        var value = parseFloat(splitUnit[0]);
        var exp = (splitUnit.length === 1) ? 0 : parseInt(unitMap[splitUnit[1]]);
        
        var temp = value * Math.pow(10, exp);
        
        convertedNumber += temp;
    }
    
    $('#result').text(convertedNumber);
});