Gulp generate a cache busting random string

gulpfile.js

var gulp = require('gulp');
var fs = require('fs');
var randomStr = require('randomstring');

// pick where you want the file to land
var destinationDir = '.';

// remove the file each time before generating a new one
gulp.task('clean-cache-buster', function() {
    return gulp.src([destinationDir + '/cache.buster'])
        .pipe(clean({force: true}));
});

// generate a random string used for cache busting
// Our PHP reads that file to append for the '?v=<string>' on the css/js includes
gulp.task('bust-cache', ['clean-cache-buster'], function () {
    // generate a random number between 5 - 10
    var randomNumber = Math.floor(Math.random() * 6) + 5;

    // generate a string the length of the randomNumber
    var randomString = randomStr.generate(randomNumber);

    // write the value to a file where PHP can read
    fs.writeFileSync(destinationDir + '/cache.buster', randomString);
});

gulp.task('default', ['bust-cache', 'other-tasks-here']);

/* 

PHP Usage

$cacheBuster = file_get_contents("/path/to/cache.buster");
<link rel="stylesheet" type="text/css" href="/path/to/style.css?v=<? echo $cacheBuster; ?>">
<script src="/path/to/file.js?v=<? echo $cacheBuster; ?>"></script>

*/