Week 7 Notes
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Call and Apply Methods
The call() method can be used to set the value of this inside a function to an object that is provided as the first argument. The apply() method is similar except the arguments are an array.
Call Example
Apply Example
Memoization
You can save a result in a cache property then return a value from the cache.
Immediately Invoked Function Expressions
This is an anonymous function that is invoked when it's defined.
Initialization Code
This is used when you have code that you won't need again like a welcome message.
Functions That Define and Rewrite Themselves
You can assign an anonymous function to a variable with the same name as the function. This allows the function to call itself, define itself, and redefine itself.
Recursive Functions
This function will invoke itself until a certain condition is met.
Event-driven Asynchronous Programming
By using callbacks, we can make sure that the rest of the program doesn't get stuck waiting for other parts. When a task is completed, the callback will be invoked before returning to the rest of the program.
Promises
Promises can do what callbacks do, but they simplify the process.
Promise Life Cycle
- Created: pending
- Operation Taking Place: Unsettled
- Operation Completed: Settled
A settled promise can have two outcomes:
- Resolved: Operation completed
- Rejected: Operation didn't work as expected, wasn't completed, or had an error
Creating a Promise
You create a promise with a constructor. It takes a function called an executor as an argument. It also accepts the resolve() function and reject() function as arguments. When you chain multiple promises, the next promise will only begin after the last has finished.
Currying
Allows you to turn one function into a series of functions.