website/experiments/infipage/index.html

---
title: Infipage
description: Outdoing all other websites with <b>INFINITE PAGES!</b>
url: /infipage/p
---
<style>
    #prev, #next {
        text-decoration: none;
    }
    
    #main {
        padding-top: 10vh;
        font-size: 2em;
        display: flex;
        justify-content: space-around;
    }
    
    #main.mobile {
        display: block;
        text-align: center;
    }
    
    #pagecount {
        max-width: 70vw;
        overflow-wrap: break-word;
    }
    
    #error {
        padding-top: 0.5em;
        color: red;
        text-align: center;
    }
</style>
<div id="main">
    <a id="prev">Previous Page</a>
    <div id="pagecount"></div>
    <a id="next">Next Page</a>
</div>
<div id="error"></div>
<script src="/assets/js/big.js"></script>
<script>
    Big.PE = Infinity
    Big.DP = 0
    Big.RM = 0
    
    // From MDN somewhere
    if (!String.prototype.startsWith) {
        String.prototype.startsWith = function(search, pos) {
            return this.substr(!pos || pos < 0 ? 0 : +pos, search.length) === search;
        };
    }

    // not quite base64 alphabet
    var alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstvuwxyz0123456789-_~.:@"
    var alphabetMapping = {}
    for (var i = 0; i < alphabet.length; i++) { alphabetMapping[alphabet[i]] = i }
    console.log("alphabet is", alphabet, "chars")
    var base = Big(alphabet.length)

    function encodeBignum(b) {
        var out = ""
        var curr = b
        // Pretend it's a positive int until the end
        if (b.s === -1) { curr = b.times(-1) }
        var byte = 0
        while (!curr.eq(0)) {
            var now = curr.mod(base)
            out += alphabet[+now]
            curr = curr.div(base)
        }
        var start = b.s === -1 ? "n" : "p"
        return start + out
    }
    
    function decodeBignum(str) {
        // If string is not tagged with its sign, it's just a regular number
        // backward compatibility only
        if (!str.startsWith("n") && !str.startsWith("p")) {
            return Big(str)
        }
        
        var start = str.substring(0, 1)
        
        var main = str.substring(1)
        var out = Big(0)
        var bvals = main.split("").map(function(x) { return alphabetMapping[x] })
        // Add each char's value to string, multiplied by the base to the power of its position in string
        bvals.forEach(function(val, position) {
            var thisByte = Big(val).times(base.pow(position))
            out = out.plus(thisByte)
        })
        if (start === "n") { out = out.times(-1) }
        return out
    }
    
    var page
    var pageString
    var prev = document.querySelector("#prev"), next = document.querySelector("#next"), count = document.querySelector("#pagecount"), main = document.querySelector("#main"), error = document.querySelector("#error")
    function loadPage() {
        try {
            var afterSlash = /infipage\/([A-Za-z0-9_~.:@-]*)/.exec(window.location.pathname)[1]
            page = decodeBignum(afterSlash)
        } catch(e) {
            console.warn("Page Number Decode Failure")
            console.warn(e)
            error.innerText = "Page number invalid - " + e + ". Defaulting to 0."
            page = Big(0)
        }
        pageString = page.toString()
        console.log("Page", pageString)
        var canonical = encodeBignum(page)
        if (canonical !== afterSlash) {
            console.log(canonical, afterSlash, "Mismatch!")
            window.location.href = "/infipage/" + canonical
        }
        prev.href = "/infipage/" + encodeBignum(page.minus(1))
        next.href = "/infipage/" + encodeBignum(page.plus(1))
        pagecount.innerText = "Page " + pageString
    }
    loadPage()
    if ("ontouchstart" in window) { main.classList.add("mobile") }
</script>
<script>
// interface with arbitrary points
window.addEventListener("load", function() {
    if ("points" in window) { 
        console.log("running update")
        points.then(points => points.updateMetric("greatestInfipage", function(current) {
            console.log("updated", current, pageString)
            if (!current || page.abs().gt(Big(current))) { return pageString }
            else { return current }
        }))
    }
})
</script>