gulpfile.js

var gulp = require('gulp');
var ts = require('gulp-typescript');
var merge = require('merge2');
 
var tsProject = ts.createProject('tsconfig.json');
 
gulp.task('scripts', function() {
    var tsResult = tsProject.src()
        .pipe(ts(tsProject));
 
    return merge([ // Merge the two output streams, so this task is finished when the IO of both operations are done. 
        tsResult.dts.pipe(gulp.dest('release/definitions')),
        tsResult.js.pipe(gulp.dest('release/js'))
    ]);
});
 
gulp.task('watch', ['scripts'], function() {
    gulp.watch(tsPreoject.src(), ['scripts']);
});