src/Linkifier.ts

   1 /**
   2  * @license MIT
   3  */
   4
   5 export type LinkHandler = (uri: string) => void;
   6
   7 type LinkMatcher = {id: number, regex: RegExp, matchIndex?: number, handler: LinkHandler};
   8
   9 const protocolClause = '(https?:\\/\\/)';
  10 const domainCharacterSet = '[\\da-z\\.-]+';
  11 const negatedDomainCharacterSet = '[^\\da-z\\.-]+';
  12 const domainBodyClause = '(' + domainCharacterSet + ')';
  13 const tldClause = '([a-z\\.]{2,6})';
  14 const ipClause = '((\\d{1,3}\\.){3}\\d{1,3})';
  15 const portClause = '(:\\d{1,5})';
  16 const hostClause = '((' + domainBodyClause + '\\.' + tldClause + ')|' + ipClause + ')' + portClause + '?';
  17 const pathClause = '(\\/[\\/\\w\\.-]*)*';
  18 const queryStringClause = '(\\?[\\w\\[\\]\\(\\)\\/\\?\\!#@$&\'*+,:;]*)?';
  19 const negatedPathCharacterSet = '[^\\/\\w\\.-]+';
  20 const bodyClause = hostClause + pathClause + queryStringClause;
  21 const start = '(?:^|' + negatedDomainCharacterSet + ')(';
  22 const end = ')($|' + negatedPathCharacterSet + ')';
  23 const strictUrlRegex = new RegExp(start + protocolClause + bodyClause + end);
  24
  25 /**
  26  * The ID of the built in http(s) link matcher.
  27  */
  28 const HYPERTEXT_LINK_MATCHER_ID = 0;
  29
  30 /**
  31  * The time to wait after a row is changed before it is linkified. This prevents
  32  * the costly operation of searching every row multiple times, pntentially a
  33  * huge aount of times.
  34  */
  35 const TIME_BEFORE_LINKIFY = 200;
  36
  37 /**
  38  * The Linkifier applies links to rows shortly after they have been refreshed.
  39  */
  40 export class Linkifier {
  41   private _rows: HTMLElement[];
  42   private _rowTimeoutIds: number[];
  43   private _linkMatchers: LinkMatcher[];
  44   private _nextLinkMatcherId = HYPERTEXT_LINK_MATCHER_ID;
  45
  46   constructor(rows: HTMLElement[]) {
  47     this._rows = rows;
  48     this._rowTimeoutIds = [];
  49     this._linkMatchers = [];
  50     this.registerLinkMatcher(strictUrlRegex, null, 1);
  51   }
  52
  53   /**
  54    * Queues a row for linkification.
  55    * @param {number} rowIndex The index of the row to linkify.
  56    */
  57   public linkifyRow(rowIndex: number): void {
  58     const timeoutId = this._rowTimeoutIds[rowIndex];
  59     if (timeoutId) {
  60       clearTimeout(timeoutId);
  61     }
  62     this._rowTimeoutIds[rowIndex] = setTimeout(this._linkifyRow.bind(this, rowIndex), TIME_BEFORE_LINKIFY);
  63   }
  64
  65   /**
  66    * Attaches a handler for hypertext links, overriding default <a> behavior
  67    * for standard http(s) links.
  68    * @param {LinkHandler} handler The handler to use, this can be cleared with
  69    * null.
  70    */
  71   public attachHypertextLinkHandler(handler: LinkHandler): void {
  72     this._linkMatchers[HYPERTEXT_LINK_MATCHER_ID].handler = handler;
  73   }
  74
  75   /**
  76    * Registers a link matcher, allowing custom link patterns to be matched and
  77    * handled.
  78    * @param {RegExp} regex The regular expression to search for, specifically
  79    * this searches the textContent of the rows. You will want to use \s to match
  80    * a space ' ' character for example.
  81    * @param {LinkHandler} handler The callback when the link is called.
  82    * @param {number} matchIndex The index of the link from the regex.match(text)
  83    * call. This defaults to 0 (for regular expressions without capture groups).
  84    * @return {number} The ID of the new matcher, this can be used to deregister.
  85    */
  86   public registerLinkMatcher(regex: RegExp, handler: LinkHandler, matchIndex?: number): number {
  87     if (this._nextLinkMatcherId !== HYPERTEXT_LINK_MATCHER_ID && !handler) {
  88       throw new Error('handler cannot be falsy');
  89     }
  90     const matcher: LinkMatcher = {
  91       id: this._nextLinkMatcherId++,
  92       regex,
  93       handler,
  94       matchIndex
  95     };
  96     this._linkMatchers.push(matcher);
  97     return matcher.id;
  98   }
  99
 100   /**
 101    * Deregisters a link matcher if it has been registered.
 102    * @param {number} matcherId The link matcher's ID (returned after register)
 103    * @return {boolean} Whether a link matcher was found and deregistered.
 104    */
 105   public deregisterLinkMatcher(matcherId: number): boolean {
 106     // ID 0 is the hypertext link matcher which cannot be deregistered
 107     for (let i = 1; i < this._linkMatchers.length; i++) {
 108       if (this._linkMatchers[i].id === matcherId) {
 109         this._linkMatchers.splice(i, 1);
 110         return true;
 111       }
 112     }
 113     return false;
 114   }
 115
 116   /**
 117    * Linkifies a row.
 118    * @param {number} rowIndex The index of the row to linkify.
 119    */
 120   private _linkifyRow(rowIndex: number): void {
 121     const row = this._rows[rowIndex];
 122     if (!row) {
 123       return;
 124     }
 125     const text = row.textContent;
 126     for (let i = 0; i < this._linkMatchers.length; i++) {
 127       const matcher = this._linkMatchers[i];
 128       const uri = this._findLinkMatch(text, matcher.regex, matcher.matchIndex);
 129       if (uri) {
 130         this._doLinkifyRow(rowIndex, uri, matcher.handler);
 131         // Only allow a single LinkMatcher to trigger on any given row.
 132         return;
 133       }
 134     }
 135   }
 136
 137   /**
 138    * Linkifies a row given a specific handler.
 139    * @param {number} rowIndex The index of the row to linkify.
 140    * @param {string} uri The uri that has been found.
 141    * @param {handler} handler The handler to trigger when the link is triggered.
 142    */
 143   private _doLinkifyRow(rowIndex: number, uri: string, handler?: LinkHandler): void {
 144     // Iterate over nodes as we want to consider text nodes
 145     const nodes = this._rows[rowIndex].childNodes;
 146     for (let i = 0; i < nodes.length; i++) {
 147       const node = nodes[i];
 148       const searchIndex = node.textContent.indexOf(uri);
 149       if (searchIndex >= 0) {
 150         const linkElement = this._createAnchorElement(uri, handler);
 151         if (node.textContent.trim().length === uri.length) {
 152           // Matches entire string
 153           if (node.nodeType === Node.TEXT_NODE) {
 154             this._replaceNode(node, linkElement);
 155           } else {
 156             const element = (<HTMLElement>node);
 157             if (element.nodeName === 'A') {
 158               // This row has already been linkified
 159               return;
 160             }
 161             element.innerHTML = '';
 162             element.appendChild(linkElement);
 163           }
 164         } else {
 165           // Matches part of string
 166           this._replaceNodeSubstringWithNode(node, linkElement, uri, searchIndex);
 167         }
 168       }
 169     }
 170   }
 171
 172   /**
 173    * Finds a link match in a piece of text.
 174    * @param {string} text The text to search.
 175    * @param {number} matchIndex The regex match index of the link.
 176    * @return {string} The matching URI or null if not found.
 177    */
 178   private _findLinkMatch(text: string, regex: RegExp, matchIndex?: number): string {
 179     const match = text.match(regex);
 180     if (!match || match.length === 0) {
 181       return null;
 182     }
 183     return match[typeof matchIndex !== 'number' ? 0 : matchIndex];
 184   }
 185
 186   /**
 187    * Creates a link anchor element.
 188    * @param {string} uri The uri of the link.
 189    * @return {HTMLAnchorElement} The link.
 190    */
 191   private _createAnchorElement(uri: string, handler: LinkHandler): HTMLAnchorElement {
 192     const element = document.createElement('a');
 193     element.textContent = uri;
 194     if (handler) {
 195       element.addEventListener('click', () => handler(uri));
 196     } else {
 197       element.href = uri;
 198       // Force link on another tab so work is not lost
 199       element.target = '_blank';
 200     }
 201     return element;
 202   }
 203
 204   /**
 205    * Replace a node with 1 or more other nodes.
 206    * @param {Node} oldNode The node to replace.
 207    * @param {Node[]} newNodes The new nodes to insert in order.
 208    */
 209   private _replaceNode(oldNode: Node, ...newNodes: Node[]): void {
 210     const parent = oldNode.parentNode;
 211     for (let i = 0; i < newNodes.length; i++) {
 212       parent.insertBefore(newNodes[i], oldNode);
 213     }
 214     parent.removeChild(oldNode);
 215   }
 216
 217   /**
 218    * Replace a substring within a node with a new node.
 219    * @param {Node} targetNode The target node; either a text node or a <span>
 220    * containing a single text node.
 221    * @param {Node} newNode The new node to insert.
 222    * @param {string} substring The substring to replace.
 223    * @param {number} substringIndex The index of the substring within the string.
 224    */
 225   private _replaceNodeSubstringWithNode(targetNode: Node, newNode: Node, substring: string, substringIndex: number): void {
 226     let node = targetNode;
 227     if (node.nodeType !== Node.TEXT_NODE) {
 228       node = node.childNodes[0];
 229     }
 230
 231     // The targetNode will be either a text node or a <span>. The text node
 232     // (targetNode or its only-child) needs to be replaced with newNode plus new
 233     // text nodes potentially on either side.
 234     if (node.childNodes.length === 0 && node.nodeType !== Node.TEXT_NODE) {
 235       throw new Error('targetNode must be a text node or only contain a single text node');
 236     }
 237
 238     const fullText = node.textContent;
 239
 240     if (substringIndex === 0) {
 241       // Replace with <newNode><textnode>
 242       const rightText = fullText.substring(substring.length);
 243       const rightTextNode = document.createTextNode(rightText);
 244       this._replaceNode(node, newNode, rightTextNode);
 245     } else if (substringIndex === targetNode.textContent.length - substring.length) {
 246       // Replace with <textnode><newNode>
 247       const leftText = fullText.substring(0, substringIndex);
 248       const leftTextNode = document.createTextNode(leftText);
 249       this._replaceNode(node, leftTextNode, newNode);
 250     } else {
 251       // Replace with <textnode><newNode><textnode>
 252       const leftText = fullText.substring(0, substringIndex);
 253       const leftTextNode = document.createTextNode(leftText);
 254       const rightText = fullText.substring(substringIndex + substring.length);
 255       const rightTextNode = document.createTextNode(rightText);
 256       this._replaceNode(node, leftTextNode, newNode, rightTextNode);
 257     }
 258   }
 259 }