Created
May 22, 2020 00:06
-
-
Save serweb-labs/775c18de414feae3e84b429cb3640be8 to your computer and use it in GitHub Desktop.
two functions tocheck if a text is emoji regular expression based and canvas based
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| // regular expression based | |
| function isEmoji(text) { | |
| return (new RegExp(/[\uD800-\uDBFF]/g).test(text) && new RegExp(/[\uDC00-\uDFFF]/g).test(text)); | |
| } | |
| // canvas bases, slow and depend if the system can draw the emoji | |
| function isEmojiCanvas(text) { | |
| const ArrayLikeToString = arg => Array.prototype.toString.call(arg); | |
| const getTextFeature = (text, color) => { | |
| try { | |
| const canvas = document.createElement('canvas') | |
| canvas.width = 1; | |
| canvas.height = 1; | |
| const ctx = canvas.getContext('2d'); | |
| ctx.textBaseline = 'top'; | |
| ctx.font = '100px "Segoe UI Emoji", "Segoe UI Symbol", "Segoe UI", "Apple Color Emoji", "Twemoji Mozilla", "Noto Color Emoji", "EmojiOne Color", "Android Emoji"'; | |
| ctx.fillStyle = color; | |
| ctx.scale(0.01, 0.01); | |
| ctx.fillText(text, 0, 0); | |
| return ctx.getImageData(0, 0, 1, 1).data | |
| } catch (e) { | |
| return false | |
| } | |
| } | |
| const feature1 = getTextFeature(text, '#000'); | |
| const feature2 = getTextFeature(text, '#fff'); | |
| if (feature1 && feature2) { | |
| const feature1Str = ArrayLikeToString(feature1) | |
| const feature2Str = ArrayLikeToString(feature2) | |
| return feature1Str === feature2Str && feature1Str !== '0,0,0,0'; | |
| } | |
| return false; | |
| } | |
| const text = "😚 hello 🤭, how are you? 👌" | |
| console.log("regular expression based:") | |
| // don't use foreach | |
| // or the emoji is splitted | |
| for (const ch of text) { | |
| if (isEmoji(ch)) { | |
| console.log("is emoji", ch) | |
| } | |
| else { | |
| console.log("no is emoji", ch) | |
| } | |
| } | |
| console.log("canvas based based:") | |
| // don't use foreach | |
| // or the emoji is splitted | |
| for (const ch of text) { | |
| if (isEmojiCanvas(ch)) { | |
| console.log("is emoji", ch) | |
| } | |
| else { | |
| console.log("no is emoji", ch) | |
| } | |
| } |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment