Creating Your Own useMemo Hook in Plain JavaScript: A Step-by-Step Guide

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In this article, we will be discussing how to create your own version of the useMemo hook in plain JavaScript. The useMemo hook is a powerful tool in React for optimizing the performance of your application by memoizing the results of a function, so that it only re-renders when the dependencies of that function have changed.

Creating your own version of useMemo in plain JavaScript is a great way to gain a deeper understanding of how this hook works and to have more control over your application’s performance. In this article, we will be creating a simple implementation of useMemo in JavaScript, without the need for any additional libraries or frameworks.

First, let’s define a simple function called useMyMemo that takes in two arguments: fn and dependencies. The fn argument is the function that we want to memoize, while the dependencies argument is an array of values that our function depends on.

function useMyMemo(fn, dependencies) {
    // Code goes here
}

Next, we will need to create a variable to store the memoized result of our function. We can use a simple variable called result for this.

function useMyMemo(fn, dependencies) {
    let result = fn();
}

Now that we have our result variable, we need to create a way to check if the dependencies of our function have changed. We can do this by comparing the current values of our dependencies with the previous values. To store the previous values, we can create a new variable called prevDependencies.

function useMyMemo(fn, dependencies) {
    let result = fn();
    let prevDependencies = dependencies;
}

Finally, we need to create a way to update the result variable when the dependencies have changed. We can do this by using the Array.prototype.every() method to compare the current values of our dependencies with the previous values. If any of the values have changed, we can update the result variable by calling the fn function again.

function useMyMemo(fn, dependencies) {
    let result = fn();
    let prevDependencies = dependencies;
    
    if (!dependencies.every((val, i) => val === prevDependencies[i])) {
        result = fn();
        prevDependencies = dependencies;
    }
    return result;
}

And that’s it! With this simple implementation of useMemo in JavaScript, you can now easily memoize the results of a function and improve the performance of your application.

In conclusion, creating your own version of the useMemo hook in plain JavaScript is a great way to gain a deeper understanding of how this hook works and to have more control over your application’s performance. By following the steps outlined in this article, you can easily create your own useMemo hook in JavaScript without the need for any additional libraries or frameworks.

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