Bookmarklet to find bigger version of an image on tumblr.

bookmarklet.md

Copy this link and create bookmark with this as it's URL in your bookmark toolbar:

javascript:(function(){"use strict";function t(t){function l(e){var t=new XMLHttpRequest;t.onload=function(){if(this.status>=200&&this.status<400){a.push(e)}};t.onloadend=c;t.open("HEAD",r+e+s,true);t.send();++f}function c(){--f;if(f===0){if(a.length>0){a.sort(function(e,t){return e-t});var e=r+a[a.length-1]+s;location.href=e}else{alert("No bigger image found.")}}}var n=/^(.*_)(\d+)(\.[a-z]+)$/i.exec(t);if(!n){alert("Not a tumblr image URL.");return}var r=n[1];var i=Number(n[2]);var s=n[3];var o=null;for(var u=0;u<e.length;++u){if(e[u]>i){o=u;break}}if(o===null){alert("There is no bigger known size.");return}var a=[];var f=0;for(var u=o;u<e.length;++u){l(e[u])}}var e=[75,100,250,400,500,1280];t(location.href)})()

Then when you view a tumblr image and suspect that there is a bigger version of it click this bookmarklet.

source.js

(function () {
	"use strict";

	var Sizes = [75, 100, 250, 400, 500, 1280];

	findBigger(location.href);

	function findBigger (url) {
		var m = /^(.*_)(\d+)(\.[a-z]+)$/i.exec(url);

		if (!m) {
			alert("Not a tumblr image URL.");
			return;
		}
		
		var prefix = m[1];
		var size = Number(m[2]);
		var suffix = m[3];

		var index = null;
		for (var i = 0; i < Sizes.length; ++ i) {
			if (Sizes[i] > size) {
				index = i;
				break;
			}
		}

		if (index === null) {
			alert("There is no bigger known size.");
			return;
		}

		var supported = [];
		var pending = 0;
		for (var i = index; i < Sizes.length; ++ i) {
			testSize(Sizes[i]);
		}

		function testSize (size) {
			var xhr = new XMLHttpRequest();

			xhr.onload = function () {
				if (this.status >= 200 && this.status < 400) {
					console.log("supported size:",size);
					supported.push(size);
				}
			};

			xhr.onloadend = loadend;

			xhr.open('HEAD',prefix + size + suffix,true);
			xhr.send();

			++ pending;
		}

		function loadend () {
			-- pending;
			if (pending === 0) {
				if (supported.length > 0) {
					supported.sort(function (lhs, rhs) { return lhs - rhs; });
					var newUrl = prefix + supported[supported.length - 1] + suffix;
					console.log("found bigger:",newUrl);
					location.href = newUrl;
				}
				else {
					alert("No bigger image found.");
				}
			}
		}
	}
})();