simplified add gcode

src/gcode.js

@@ -13,19 +13,21 @@ export default class {
 	}
 
 	_addGCode (command) {
-		var str = '';
-		var first = true;
+		let str = '';
+		let first = true;
 
-		for (var i in command) {
+		for (const action in command) {
+			const value = command[action];
+			const currentValue = this.current[action];
 			if (first) {
-				str = i + command[i];
+				str = action + value;
 
 				first = false;
 			}
-			else if (this.current[i] !== command[i]) {
-				str += ' ' + i + command[i];
+			else if (currentValue !== value) {
+				str += ` ${action}${value}`;
 
-				this.current[i] = command[i];
+				this.current[action] = value;
 			}
 		}