Hackernoon logoHow to Add Auto Caching to Your JS Template Engine by@shadowtime2000

How to Add Auto Caching to Your JS Template Engine

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If you are looking at this you are probably wondering who I am.

In one of my articles I showed you how to create a simple JS template engine. In this article I will show you how to add simple caching to the compilation of our templates.

How Caching Works with JS Template Engines

Caching with our template engine is pretty simple. We just keep a key value object and use template strings as keys and functions as values. This will make subsequent uses of a template faster.

Implementing it inside Compile

All our compile function is this:

const compile = (template) => {
    return new Function("data", "return " + compileToString(template))

Let's rename this to


const compileToFunction = (template) => {
    return new Function("data", "return " + compileToString(template))

Now let's create a cache. We will use a 

 for this.

const cache = new Map();

Now let's add a 

 function which uses this

All we need to do is check if the 

. If not, we need to create it and set it. If it does have it, we just need to return it.

const compile = (template) => {
    if (cache.has(template)) {
        return cache.get(template);
    } else {
        const compiledFunction = compileToFunction(template);
        cache.set(template, compiledFunction);
        return compiledFunction;

Changing Our Render Function

Currently our 

 function just uses some Regex to replace all the values.

var render = (template, data) => {
    return template.replace(/{{(.*?)}}/g, (match) => {
        return data[match.split(/{{|}}/).filter(Boolean)[0]]

I think we should change it to use 

 under the hood for faster automatic caching. It is pretty simple to implement, we just need to run
 and then run that function with 

const render = (template, data) => {
    return compile(template)(data);


In this tutorial I showed how to extend the template engine we made in a previous post with caching for faster compilation and rendering.

Other Articles You Might Like

  1. Creating a JS Template Engine
  2. 14 JS Template Engines

Also published here.


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