What is the significance of employing the `var` keyword in Vue.js?

As I dive into tutorials and browse through code snippets while immersing myself in learning this framework, I've noticed a common trend - the use of var for declarations. This practice seems prevalent across resources, including the official Vue documentation.

Full disclosure: I'm a beginner when it comes to Vue, so my understanding is limited, and I have yet to find a definitive answer.

Another point of contention arises with assumptions surrounding property names:

new Vue({
  data: data
})

compared to

new Vue({
  data
})

I can't help but wonder if my assumption that ES6's const and let should be the norm is misguided. Why stick with var in Vue.js? Could there be compatibility issues with ES6?

javascriptvue.js

Answer №1

Why do the developers opt for var over ES6 features in the documentation? Some might argue it's to cater to the "lowest common denominator," meaning the least advanced browsers.

Vue can be easily added using a simple <script> tag (UMD / global, no build system required) and is compatible with all ES5-compliant browsers (including IE9+), which explains why they maintain consistency in their documentation.

It’s important to choose what you...

  1. Feel comfortable utilizing, and
  2. Is supported by the production environment
    • Your build system (if applicable) can assist in transpiling ES6 code to a lower language standard

Answer №2

In addition to the arguments revolving around the lowest common denominator, it is worth noting that var and let operate with different semantics.

With var, variables are function-scoped and subject to hoisting. On the other hand, when using let, variables are block-scoped and do not get hoisted.

Therefore, despite the standardization of let and const, it is unlikely that they will completely replace var in the near future.

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