how to join js to html code example

Example 1: how to add script in html head

<script src="script.js" defer></script>

<!--just add defer attribute so script will execute at last-->

Example 2: join in array

var a = ['Wind', 'Water', 'Fire'];
a.join();      // 'Wind,Water,Fire'
a.join(', ');  // 'Wind, Water, Fire'
a.join(' + '); // 'Wind + Water + Fire'
a.join('');    // 'WindWaterFire'