I have headers in <h1>
through <h6>
tags. Is there a way that I can use JavaScript to generate a table of contents for the contents that serves as anchor tags as well?
I would like the output to be something like:
<ol>
<li>Header 1</li>
<li>Header 1</li>
<li>Header 2</li>
<li>Header 3</li>
</ol>
I am not currently using a JavaScript framework, but I don't see why I couldn't use one.
I am also looking for something done, since I'm guessing this is a common problem, but if not, a starting point to roll my own would be good.
I couldn't resist putting together a quick implementation.
Add the following script anywhere on your page:
window.onload = function () {
var toc = "";
var level = 0;
document.getElementById("contents").innerHTML =
document.getElementById("contents").innerHTML.replace(
/<h([\d])>([^<]+)<\/h([\d])>/gi,
function (str, openLevel, titleText, closeLevel) {
if (openLevel != closeLevel) {
return str;
}
if (openLevel > level) {
toc += (new Array(openLevel - level + 1)).join("<ul>");
} else if (openLevel < level) {
toc += (new Array(level - openLevel + 1)).join("</ul>");
}
level = parseInt(openLevel);
var anchor = titleText.replace(/ /g, "_");
toc += "<li><a href=\"#" + anchor + "\">" + titleText
+ "</a></li>";
return "<h" + openLevel + "><a name=\"" + anchor + "\">"
+ titleText + "</a></h" + closeLevel + ">";
}
);
if (level) {
toc += (new Array(level + 1)).join("</ul>");
}
document.getElementById("toc").innerHTML += toc;
};
Your page should be structured something like this:
<body>
<div id="toc">
<h3>Table of Contents</h3>
</div>
<hr/>
<div id="contents">
<h1>Fruits</h1>
<h2>Red Fruits</h2>
<h3>Apple</h3>
<h3>Raspberry</h3>
<h2>Orange Fruits</h2>
<h3>Orange</h3>
<h3>Tangerine</h3>
<h1>Vegetables</h1>
<h2>Vegetables Which Are Actually Fruits</h2>
<h3>Tomato</h3>
<h3>Eggplant</h3>
</div>
</body>
You can see it in action at https://codepen.io/scheinercc/pen/KEowRK (old link: http://magnetiq.com/exports/toc.htm (Works in IE, FF, Safari, Opera))