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WTF is Lodash?

Apr 21, 2020 JavaScript

Lodash is a JavaScript library that brings a set of utilities on top of vanilla JavaScript (i.e. JS without any extras). It's a funny play on Underscore.js, and has since become a superset of Underscore.

Both of these libraries use their moniker as a representation of the object that accesses all their utility methods — the underscore (i.e. _).

A Lodash Example

Whenever I find myself doing something stupid with JavaScript, I usually take a step back and realize that someone has probably solved the problem I'm solving before, and there's a better way to do what I'm doing.

When that involves manipulating an object, array, or string, Lodash often comes to my rescue. Let's look at a couple examples.

Let's say I have a deeply nested object, obj:

const obj = {
  a: [
    {
      b: {
        c: "Hi there!"
      }
    }
  ]
}

I would be able to get to c with obj.a[0].b.c. But what if I didn't know that path, but I had to set it? Perhaps the structure of this object can vary. All I have is a string that represents the path at which I want to set.

const propPath = "a[0].b.c"

I could use eval, but that's generally a very bad idea. MDN's page leads with:

Warning: Executing JavaScript from a string is an enormous security risk. It is far too easy for a bad actor to run arbitrary code when you use eval(). See Never use eval()! , below.

I've found myself in a situation where I couldn't figure another clean way to achieve this. But, lo and behold, Lodash had the answer in _.set.

That's just one of many scenarios in which I've found myself where Lodash has come to the rescue.

Underscore Not Necessary Today

I'll also point out that the underscore is not necessary today. In fact, I prefer not to use it. It's too generic of a character when the word lodash works fine. Instead, with ES6 imports, we can give the object representing Lodash any name we want, as that object is the library's default export.

import lodash from "lodash"

lodash.set(obj, "a[0].b.c")

Bundle Size

While it's decreased over the years, Lodash is a large package to bring into a project when you may only need one or two of its features. Fortunately, there's a means to install functions independently.

For example, installing the entire library looks like this:

$ npm install lodash

But, you could install a single function like this:

$ npm install lodash.set

Because I'm typically only using a few functions here and there, I tend to bring in the individual libraries until I'm using enough that it seems more practical to have the entire object at my disposal. It's a balance between bundle size and the productivity of writing code.

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