How to Add Auto Caching to Your JS Template Engine

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

compileToFunction

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

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

Map

for this.

const cache = new Map();

Now let's add a

compile

function which uses this

cache

All we need to do is check if the

cache.has(template)

. 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

render

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

compile

under the hood for faster automatic caching. It is pretty simple to implement, we just need to run

compile

and then run that function with

data

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

Conclusion

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

How to Add Auto Caching to Your JS Template Engine

How Caching Works with JS Template Engines

Implementing it inside Compile

Changing Our Render Function

Conclusion

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