chore: start of a webworker

package.json

@@ -55,7 +55,8 @@
     "style-loader": "^2.0.0",
     "webpack": "^4.44.2",
     "webpack-cli": "^4.0.0",
-    "webpack-dev-server": "^3.11.0"
+    "webpack-dev-server": "^3.11.0",
+    "worker-loader": "^3.0.8"
   },
   "scripts": {
     "build": "npm run test && npm run build:dist",

src/diff-view.js

@@ -993,10 +993,27 @@ CodeMirrorDiffView.prototype._diff = function() {
 	}
 	const lhs = this.editor.lhs.getValue();
 	const rhs = this.editor.rhs.getValue();
-	const comparison = new diff(lhs, rhs, this.settings);
-	this.changes = DiffParser(comparison.normal_form());
-	if (this.settings._debug.includes('change')) {
-		traceTimeEnd(' change#_diff');
+	/*
+	if (window.Worker) {
+		if (!this._diffWorker) {
+			trace(' change#_diff creating diff worker');
+			// this._diffWorker = new Worker('./diff-worker.js');
+			this._diffWorker = new Worker(new URL('./diff-worker.js', import.meta.url));
+			this._diffWorker.onchange = (ev) => {
+				this.changes = ev.data;
+				this._clear();
+				this._changed();
+			}
+		}
+		trace(' change#_diff starting worker');
+		this._diffWorker.postMessage({ lhs, rhs });
+	} else 
+	*/{
+		const comparison = new diff(lhs, rhs, this.settings);
+		this.changes = DiffParser(comparison.normal_form());
+		if (this.settings._debug.includes('change')) {
+			traceTimeEnd(' change#_diff');
+		}
 	}
 };
 

src/diff-worker.js

@@ -0,0 +1,8 @@
+const diff = require('./diff');
+
+onmessage = function (ev) {
+	const { lhs, rhs } = ev;
+	const compare = new diff(lhs, rhs, this.settings);
+	const changes = DiffParser(compare.normal_form());
+	postMessage(changes);
+};

webpack.dev.js

@@ -23,6 +23,11 @@ module.exports = {
 			}, {
 				loader: 'css-loader'
 			}]
+		}, {
+			test: /worker\.js$/,
+			use: {
+				loader: 'worker-loader'
+			}
 		}]
 	},