let instructor = 'James';
instructor = 'Richard';
console.log(instructor);
The output is “Richard”
Use cases
The big question is when should you use
let
and
const
? The general rule of thumb is as follows:
- use
let
when you plan to reassign new values to a variable, and - use
const
when you don’t plan on reassigning new values to a variable.
What about var?
Is there any reason to use
var
anymore? Not really.
There are some arguments that can be made for using
var
in situations where you want to globally define variables, but this is often considered bad practice and should be avoided. From now on, we suggest ditching
var
in place of using
let
and
const
.
The right use:
/*
* Programming Quiz: Using Let and Const (1-1)
*/
const CHARACTER_LIMIT = 255;
const posts = [
"#DeepLearning transforms everything from self-driving cars to language translations. AND it's our new Nanodegree!",
"Within your first week of the VR Developer Nanodegree Program, you'll make your own virtual reality app",
"I just finished @udacity's Front-End Web Developer Nanodegree. Check it out!"
];
// prints posts to the console
function displayPosts() {
for (let i = 0; i < posts.length; i++) {
console.log(posts[i].slice(0, CHARACTER_LIMIT));
}
}
displayPosts();
Output:
#DeepLearning transforms everything from self-driving cars to language translations. AND it's our new Nanodegree!
Within your first week of the VR Developer Nanodegree Program, you'll make your own virtual reality app
I just finished @udacity's Front-End Web Developer Nanodegree. Check it out!
Source: https://www.udacity.com/course/es6-javascript-improved–ud356