custom.js

function addCopyButtonToCode(){
// get all code elements
var allCodeBlocksElements = $( "div.highlight pre" );

// For each element, do the following steps
allCodeBlocksElements.each(function(ii) {
// define a unique id for this element and add it
var currentId = "codeblock" + (ii + 1);
$(this).attr('id', currentId);

// create a button that's configured for clipboard.js
// point it to the text that's in this code block
// add the button just after the text in the code block w/ jquery
var clipButton = '<button class="btn copybtn" data-clipboard-target="#' + currentId + '"><img src="https://clipboardjs.com/assets/images/clippy.svg" width="13" alt="Copy to clipboard"></button>';
   $(this).after(clipButton);
});

// tell clipboard.js to look for clicks that match this query
new Clipboard('.btn');
}

$(document).ready(function () {
// Once the DOM is loaded for the page, attach clipboard buttons
addCopyButtonToCode();
});