basic system/browser fingerprinting function for use as a simple but robust user id

fingerprint.js

// fingerprint : basic system/browser fingerprinting function
// for use as a simple but robust user id
function fingerprint() {
    // hash : simple hash-like function, not guaranteed to return same-size data
    //   or change output greatly on input changes
    let hash = function (input) {
        let temp = JSON.stringify(input),
            out = BigInt(0)
        for (let i = 0; i < temp.length; i++) {
            out ^= BigInt(temp.charCodeAt(i)) << BigInt(i % 128)
        }
        return out.toString(16)
    }

    // webGlInfo : basic information about WebGL, falling back to basic canvas
    //   sizing if unable to access debug info
    let webGlInfo = function () {
        let canvas = document.createElement('canvas'),
            webgl = canvas.getContext('webgl'),
            render_debug = webgl?.getExtension('WEBGL_debug_renderer_info')
        if (!render_debug) return [canvas.width, canvas.height]
        return [
            webgl.getParameter(render_debug.UNMASKED_VENDOR_WEBGL),
            webgl.getParameter(render_debug.UNMASKED_RENDERER_WEBGL)
        ].join()
    }

    // canvasData : information about canvas rendering used for fingerprinting,
    //   returns 0 if unable to read from canvas
    let canvasData = function () {
        let canvas = document.createElement('canvas'),
            ctx = canvas.getContext('2d')
        canvas.width = 180
        canvas.height = 50
        ctx.fillStyle = 'green'
        ctx.fillRect(12.4, 6.5, 17.0, 18.6)
        ctx.strokeStyle = '#ff00004c'
        ctx.strokeText('Sphinx of black quartz, judge my vow.', 10, 10)
        ctx.fillStyle = '#0000ab65'
        ctx.fillRect(0, 8, 150, 15)
        let data = ctx.getImageData(0, 0, canvas.width, canvas.height).data
        if (Math.max(...data.slice(0, 20)) > 0) return 0
        return data.join()
    }

    // fingerprinting parameters
    return hash([
        navigator.appCodeName,
        navigator.appName,
        navigator.oscpu,
        navigator.platform,
        navigator.product,
        webGlInfo(),
        hash(canvasData()),
        Object.keys(navigator.__proto__)
    ])
}