prism-line-highlight.js

(function(){

if (typeof self === 'undefined' || !self.Prism || !self.document || !document.querySelector) {
	return;
}

function $$(expr, con) {
	return Array.prototype.slice.call((con || document).querySelectorAll(expr));
}

function hasClass(element, className) {
  className = " " + className + " ";
  return (" " + element.className + " ").replace(/[\n\t]/g, " ").indexOf(className) > -1
}

// Some browsers round the line-height, others don't.
// We need to test for it to position the elements properly.
var isLineHeightRounded = (function() {
	var res;
	return function() {
		if(typeof res === 'undefined') {
			var d = document.createElement('div');
			d.style.fontSize = '13px';
			d.style.lineHeight = '1.5';
			d.style.padding = 0;
			d.style.border = 0;
			d.innerHTML = '&nbsp;<br />&nbsp;';
			document.body.appendChild(d);
			// Browsers that round the line-height should have offsetHeight === 38
			// The others should have 39.
			res = d.offsetHeight === 38;
			document.body.removeChild(d);
		}
		return res;
	}
}());

function highlightLines(pre, lines, classes) {
	var ranges = lines.replace(/\s+/g, '').split(','),
	    offset = +pre.getAttribute('data-line-offset') || 0;

	var parseMethod = isLineHeightRounded() ? parseInt : parseFloat;
	var lineHeight = parseMethod(getComputedStyle(pre).lineHeight);

	for (var i=0, range; range = ranges[i++];) {
		range = range.split('-');
					
		var start = +range[0],
		    end = +range[1] || start;
		
		var line = document.createElement('div');
		
		line.textContent = Array(end - start + 2).join(' \n');
		line.setAttribute('aria-hidden', 'true');
		line.className = (classes || '') + ' line-highlight';

		//if the line-numbers plugin is enabled, then there is no reason for this plugin to display the line numbers
		if(!hasClass(pre, 'line-numbers')) {
			line.setAttribute('data-start', start);

			if(end > start) {
				line.setAttribute('data-end', end);
			}
		}

		line.style.top = (start - offset - 1) * lineHeight + 'px';

		//allow this to play nicely with the line-numbers plugin
		if(hasClass(pre, 'line-numbers')) {
			//need to attack to pre as when line-numbers is enabled, the code tag is relatively which screws up the positioning
			pre.appendChild(line);
		} else {
			(pre.querySelector('code') || pre).appendChild(line);
		}
	}
}

function applyHash() {
	var hash = location.hash.slice(1);
	
	// Remove pre-existing temporary lines
	$$('.temporary.line-highlight').forEach(function (line) {
		line.parentNode.removeChild(line);
	});
	
	var range = (hash.match(/\.([\d,-]+)$/) || [,''])[1];
	
	if (!range || document.getElementById(hash)) {
		return;
	}
	
	var id = hash.slice(0, hash.lastIndexOf('.')),
	    pre = document.getElementById(id);

	if (!pre) {
		return;
	}
	
	if (!pre.hasAttribute('data-line')) {
		pre.setAttribute('data-line', '');
	}

	highlightLines(pre, range, 'temporary ');

	document.querySelector('.temporary.line-highlight').scrollIntoView();
}

var fakeTimer = 0; // Hack to limit the number of times applyHash() runs

Prism.hooks.add('complete', function(env) {
	var pre = env.element.parentNode;
	var lines = pre && pre.getAttribute('data-line');
	
	if (!pre || !lines || !/pre/i.test(pre.nodeName)) {
		return;
	}
	
	clearTimeout(fakeTimer);
	
	$$('.line-highlight', pre).forEach(function (line) {
		line.parentNode.removeChild(line);
	});
	
	highlightLines(pre, lines);
	
	fakeTimer = setTimeout(applyHash, 1);
});

if(window.addEventListener) {
	window.addEventListener('hashchange', applyHash);
}

})();