JSFiddle - React, Tailwind, and code Playground

HTML

<h2>Нажмите F12 чтобы увидеть результат</h2>

JavaScript

function Length(x1, x2, y1, y2) {
    this.x1 = x1;
    this.x2 = x2;
    this.y1 = y1;
    this.y2 = y2;
    this.toString = displayLength;
}

function displayLength() {
    return Math.sqrt((this.x2 - this.x1) * (this.x2 - this.x1) + (this.y2 - this.y1) * (this.y2 - this.y1));
}

var length = new Length(25, 34, 80, 71);
console.log('%clength: ' + length.toString(), "color:orange; background:blue; font-size: 18pt");