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JavaScript JavaScript and the DOM (Retiring) Getting a Handle on the DOM Selecting Elements with the Same Class Name

Greg Schudel
Greg Schudel
4,090 Points
Posted by Greg Schudel
Greg Schudel
4,090 Points

what is let in javascript?

I'm seeing the words "let" and "const" used alot in the current course I'm on (Javascript and the DOM). I'm sure this is novice of me, but what exactly is "let" and "constr"? What are the differences and usages within Javascript?

I've looked on MDN around the internet and feel like I have some inclination but not completely clear. here's a quote from one individual:

const is a signal that the identifier won’t be reassigned.

let, is a signal that the variable may be reassigned, such as a counter in a loop, or a value swap in an algorithm. It also signals that the variable will be used only in the block it’s defined in, which is not always the entire containing function.

var is now the weakest signal available when you define a variable in JavaScript. The variable may or may not be reassigned, and the variable may or may not be used for an entire function, or just for the purpose of a block or loop.

Is the safe to assume that it is correct? What is subjective and needless to know? Sorry for the confusion, I just want to be objective as possible without running into gray areas of people's opinions (there is alot of that on the internet about "code standards" now adays).

2 Answers

Jacob Mishkin
Jacob Mishkin
23,118 Points

what you have is completely correct. Think if it as do I want this variable to remain constant then use const. does this variable need to change in the course of the variable then use let. Var in Js is kinda being driven out, but you can still use it if you want to to. What const and let are doing is helping Js devs scope better when programming. Use var until you feel comfortable using const and let.

Aidan Reed
Aidan Reed
2,956 Points
Aidan Reed
Aidan Reed
2,956 Points

What I don't quite get with let and var is the scope. I totally understand the block level scoping of let, say for example in a loop but then after that I'm like meh. If you define a variable using let outside of a function it can be used anywhere much like var. If you define a variable using let inside a function or block it remains in that block. But if you define a variable using var inside a function it still can only be used in that block so other than uses with loops is that the only difference?