JavaScript(6)---Arrays

Arrays

• One way we can create an array is to use an array literal. An array literal creates an array by wrapping items in square brackets []

• Arrays in JavaScript are zero-indexed, meaning the positions start counting from 0 rather than 1.

• One of an array’s built-in properties is length and it returns the number of items in the array.

EX: console.log(objectives.length);

• One method, .push() allows us to add items to the end of an array. 

EX: 

chores.push('make dinner', 'wipe the table');

• Another array method, .pop(), removes the last item of an array.

EX: chores.pop();

• Some arrays methods that are available to JavaScript developers include: .join(), .slice(), .splice(), .shift(), .unshift(), and .concat()amongst many others. Using these built-in methods make it easier to do some common tasks when working with arrays.
• use .slice() to provid a list of things, use index in the code

EX: console.log(groceryList.slice(1, 4));

• find the index of a particular element in groceryList using .indexOf().

EX: const pastaIndex = groceryList.indexOf('pasta');

FULL EXAMPLE

In order to find the target, put the index of the three different brackets then inside of the brackets.

I learned

• Arrays are lists that store data in JavaScript.
• Arrays are created with brackets [].
• Each item inside of an array is at a numbered position, or index, starting at 0.
• We can access one item in an array using its index, with syntax like: myArray[0].
• We can also change an item in an array using its index, with syntax like myArray[0] = 'new string';
• Arrays have a length property, which allows you to see how many items are in an array.
• Arrays have their own methods, including .push() and .pop(), which add and remove items from an array, respectively.
• Arrays have many methods that perform different tasks, such as .slice() and .shift()
• Some built-in methods are mutating, meaning the method will change the array, while others are not mutating. You can always check the documentation.
• Variables that contain arrays can be declared with let or const. Even when declared with const, arrays are still mutable. However, a variable declared with const cannot be reassigned.
• Arrays mutated inside of a function will keep that change even outside the function.
• Arrays can be nested inside other arrays.
• To access elements in nested arrays chain indices using bracket notation.

What I'll be doing tomorrow... 

I'll be learning how to do Loops in JavaScript.