JSFiddle - React, Tailwind, and code Playground

JavaScript

loadEss('', 'foo', 300)

function loadEss(filename,svgName,mainWidth){
    var svgName;
    data = [
        {
            "aspectRatio": 1.247386759581881,
            "closed": 1,
            "xyData": [
                {
                    "x0": 0.53078594712060867,
                    "x1": 0.95454545454545459,
                    "x2": 0.95454545454545459,
                    "x3": 0.53078594712060867,
                    "x4": 0.53078594712060867,
                    "y0": 0.52936622215603868,
                    "y1": 0.52936622215603868,
                    "y2": 0.13179275296659432,
                    "y3": 0.13179275296659432,
                    "y4": 0.52936622215603868
                }
            ]
        },
        {
            "aspectRatio": 1.247386759581881,
            "closed": 1,
            "xyData": [
                {
                    "x0": 0.045454545454545435,
                    "x1": 0.41126403477001078,
                    "x2": 0.41126403477001078,
                    "x3": 0.045454545454545435,
                    "x4": 0.045454545454545435,
                    "y0": 0.86820724703340568,
                    "y1": 0.86820724703340568,
                    "y2": 0.44804437618547044,
                    "y3": 0.44804437618547044,
                    "y4": 0.86820724703340568
                }
            ]
        }
    ];
    data.forEach(function(kv){
        kv.xyData.forEach(function(d) {
            kv.points = [];
            aspect=1.5;
            for (var i = 0; d["x"+i] !== "" && (typeof d["x"+i] !== 'undefined'); i++) {
                kv.points.push([mainWidth*d["x"+i], mainWidth/aspect*(d["y"+i])]);
            }
            console.log(kv.points);
        });
    });

    var margin = {top: 0, right: 0, bottom: 0, left: 0},    
        width = mainWidth - margin.left - margin.right,             
        height = mainWidth/aspect - margin.top - margin.bottom; 

    svgName= d3.select("body")                         ...