GitHub Code Show Whitespace

A userscript that shows whitespace (space, tabs and carriage returns) in code blocks
当前为 2017-03-26 提交的版本，查看最新版本。
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// ==UserScript==
// @name        GitHub Code Show Whitespace
// @version     0.1.0
// @description A userscript that shows whitespace (space, tabs and carriage returns) in code blocks
// @license     https://opensource.org/licenses/MIT
// @namespace   https://github.com/Mottie
// @include     https://github.com/*
// @run-at      document-idle
// @grant       GM_addStyle
// @author      Rob Garrison
// ==/UserScript==
(() => {
	"use strict";
 
	// include em-space & en-space?
	const whitespace = {
			"%20"  : "<span class='pl-space ghcw-whitespace'> </span>",
			"%A0"  : "<span class='pl-nbsp ghcw-whitespace'>&nbsp;</span>",
			"%09"  : "<span class='pl-tab ghcw-whitespace'>\x09</span>",
			// non-matching key; applied manually
			"CRLF" : "<span class='pl-crlf ghcw-whitespace'></span>\n"
		},
		// ignore +/- in diff code blocks
		regexWS = /^(?:[+-]*)(\x20|&nbsp;|\x09)+/g,
		regexCR = /\r*\n$/,
		regexTabSize = /\btab-size-\d\b/g,
 
		toggleButton = document.createElement("div");
	toggleButton.className = "ghcw-toggle btn btn-sm tooltipped tooltipped-n";
	toggleButton.setAttribute("aria-label", "Toggle Whitespace");
	toggleButton.innerHTML = "<span class='pl-tab'></span>";
 
	GM_addStyle(`
		.highlight .blob-code-inner { tab-size: 2; }
		/* GitHub-Dark overrides the above setting */
		.highlight.ghcw-active.tab-size-2 .pl-tab { width: 1.1em; }
		.highlight.ghcw-active.tab-size-4 .pl-tab { width: 2.2em; }
		.highlight.ghcw-active.tab-size-6 .pl-tab { width: 3.3em; }
		.highlight.ghcw-active.tab-size-8 .pl-tab { width: 4.4em; }
 
		.ghcw-active .ghcw-whitespace {
			position: relative;
			display: inline-block;
		}
		.ghcw-active .ghcw-whitespace:before {
			position: absolute;
			overflow: hidden;
			opacity: .4;
			user-select: none;
		}
		.ghcw-toggle .pl-tab {
			pointer-events: none;
		}
		.ghcw-active .pl-space:before {
			content: "\\b7";
		}
		.ghcw-active .pl-nbsp:before {
			content: "\\b7";
		}
		.ghcw-active .pl-tab:before,
		.ghcw-toggle .pl-tab:before {
			content: "\\bb";
		}
		.ghcw-active .pl-crlf:before {
			content: "\\231d";
			top: -.75em;
		}
	`);
 
	let debounce,
		busy = false,
		observers = [];
 
	function addToggle() {
		$$(".file-actions").forEach(el => {
			if (!$(".ghcw-toggle", el)) {
				el.insertBefore(toggleButton.cloneNode(true), el.childNodes[0]);
			}
		});
	}
 
	function addWhitespace(block) {
		let lines, indx, len;
		if (block && !block.classList.contains("ghcw-processed")) {
			block.classList.add("ghcw-processed");
			updateTabSize(block);
			indx = 0;
 
			// class name of each code row
			lines = $$(".blob-code-inner:not(.blob-code-hunk)", block);
			len = lines.length;
 
			// loop with delay to allow user interaction
			const loop = () => {
				let line,
					// max number of DOM insertions per loop
					max = 0;
				while (max < 50 && indx < len) {
					if (indx >= len) {
						return;
					}
					line = lines[indx];
					line.innerHTML = line.innerHTML
						.replace(regexWS, s => {
							let idx = 0,
								ln = s.length,
								result = "";
							for (idx = 0; idx < ln; idx++) {
								result += whitespace[encodeURI(s[idx])] || s[idx] || "";
							}
							return result;
						})
						// remove end CRLF if it exists
						.replace(regexCR, "") +
						whitespace.CRLF;
					max++;
					indx++;
				}
				if (indx < len) {
					setTimeout(() => {
						loop();
					}, 200);
				}
			};
			loop();
		}
	}
 
	function updateTabSize(block) {
		// remove previous tab-size setting
		block.className = block.className.replace(regexTabSize, " ");
		// calculate tab-size; GitHub-Dark allows user modification
		const len = window.getComputedStyle($(".blob-code-inner", block)).tabSize;
		block.classList.add(`tab-size-${len}`);
	}
 
	function removeObservers() {
		// remove saved observers
		observers.forEach(observer => {
			if (observer) {
				observer.disconnect();
			}
		});
		observers = [];
	}
 
	function addObservers() {
		// Observe progressively loaded content
		$$(`
			.js-diff-progressive-container,
			.js-diff-load-container`
		).forEach(target => {
			const obsrvr = new MutationObserver(mutations => {
				mutations.forEach(mutation => {
					// preform checks before adding code wrap to minimize function calls
					const tar = mutation.target;
					if (!busy && tar && (
							tar.classList.contains("js-diff-progressive-container") ||
							tar.classList.contains("js-diff-load-container") ||
							tar.classList.contains("blob-wrapper")
						)
					) {
						clearTimeout(debounce);
						debounce = setTimeout(() => {
							addToggle();
						}, 500);
					}
				});
			});
			obsrvr.observe(target, {
				childList: true,
				subtree: true
			});
			observers.push(obsrvr);
		});
	}
 
	function init() {
		// toggle added to diff & file view
		addToggle();
		removeObservers();
		if (document.querySelector("#files.diff-view")) {
			addObservers();
		}
	}
 
	function $(selector, el) {
		return (el || document).querySelector(selector);
	}
 
	function $$(selector, el) {
		return Array.from((el || document).querySelectorAll(selector));
	}
 
	function closest(selector, el) {
		while (el && el.nodeType === 1) {
			if (el.matches(selector)) {
				return el;
			}
			el = el.parentNode;
		}
		return null;
	}
 
	// bind whitespace toggle button
	document.addEventListener("click", event => {
		const target = event.target;
		if (
			target.nodeName === "DIV" &&
			target.classList.contains("ghcw-toggle")
		) {
			let block = $(".highlight", closest(".file", target));
			if (block) {
				target.classList.toggle("selected");
				block.classList.toggle("ghcw-active");
				updateTabSize(block);
				addWhitespace(block);
			}
		}
	});
	document.addEventListener("pjax:end", init);
 
	setTimeout(() => {
		init();
	}, 500);
 
})();