![]() They’re called arrow functions because they have an arrow in them. What are var, let, and const similar? How are they different? Arrow FunctionsĮS6 gives us another way to write functions. If an array or object is declared using the keyword const, the contents of that array or object can be changed, but that variable name will always point to that same piece of memory. Variables declared with let can be reassigned, whereas variables declared with const cannot. Instead, if you try to access a variable declared with let or const before it’s declared, you will get a ReferenceError: Cannot access before initialization. let and const is that variables declared with let/const will not respond to hoisting in the same way var does. HoistingĪnother difference between var vs. You can read more about block statements here. What is a block? The most common ones that you will be familiar with are if statements and for loops. These two variable keywords introduce block scope. In other words, it won’t be accessible outside of the function.ĮS6 gives us two new variable keywords: let and const. We already know that variables declared (using the keyword var) inside of a function will remain scoped to that function. Scope is literally the area of code in which a variable or value can be accessed. We’re familiar with global and function scope. es5 var name = ' Brittany ' var greeting = ' Hello ' + name + ' ! ' // es6 var name = ' Brittany ' var greeting = `Hello $ !` Scope Block Scope
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