revisiting-gulp-1.js

//Watches our .jsx files and our .js. If any change, it calls the build task.
const gulp        = require('gulp');  
const runSequence = require('run-sequence');  
const gutil       = require('gulp-util');

//Boolean to hold state of watch JSX watch task
let taskOngoing = false;

//This task simply sets the taskOngoing boolean to false
gulp.task('jsxdone', function(callback) {

	gutil.log('JSX done executed');
	taskOngoing = false;
	callback();
});

//Does the 'watching'
gulp.task('watch', function() {

	//Watches .jsx files
	gulp.watch('../../public/assets/jsx/**/*.jsx', function(){
		
		//Indicate that we are running the JSX watch
		taskOngoing = true;

		gutil.log('Running JSX watch');

		//Once the jsx task is executed we will execute jsxdone
		runSequence('jsx', 'jsxdone', 'browserify');

		//THIS line is discussed below
		gutil.log('Run sequence is NOT finished');
	});

	//Watches .js files
	gulp.watch('../../public/assets/js/**/*.js', function(){

		if (!taskOngoing) {

			gutil.log('Running Javascript watch');
			runSequence('browserify');

		} else {

			//If our jsx - browserify watch task is executing then we will not allow this watch to execute
			gutil.log('SKIPPING Javascript watch. JSX task ongoing ' + (taskOngoing ? "true" : "false"));
		}
	});

	//Watches .css file for changes
	gulp.watch('../../public/assets/css/simple.css', ['cssconcat']); 
});