serweb-labs · May 22, 2020 00:06 · May 22, 2020
diff --git a/isEmoji.js b/isEmoji.js
@@ -0,0 +1,61 @@
+// 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)
+    }
+}