JSFiddle - React, Tailwind, and code Playground

HTML

<div id="app">

</div>

JavaScript

/**
 * Answer to https://stackoverflow.com/questions/58163845/javascript-parsefloat-usage-with-9-digit
 */

var app = document.querySelector("#app");


// Your string values
var strA = "10.525.142,25";
var strB = "10.525,25";

function fromUSFormatToStandard(x) {
	return x.replace(/\./g, "").replace(',', '.');
}

var a = parseFloat(fromUSFormatToStandard(strA));
var b = parseFloat(fromUSFormatToStandard(strB));


app.innerHTML = "A : " + a + " | B : " + b;