JavaScript 101 /arrays

Arrays

Arrays allow you to store multiple values in a single variable. They are like lists that can hold different types of data, such as numbers, strings, or even other arrays.

You can also create an array by using square brackets [] and separating the values with commas. You can access the values in an array using their index, which starts at 0. The index goes between square brackets., like so: arrayName[0]

Let's manipulate some arrays

Some array methods change the original array (like push, pop, splice), while others return a new array or value without changing the original (like slice, concat, join).

The basics

• arrayName.push(value, ...) - Adds one or more values to the end of the array
• arrayName.pop() - Removes the last value from the array
• arrayName.shift() - Removes the first value from the array

Intermediates

• arrayName.unshift(value, ...) - Adds one or more values to the beginning of the array
• arrayName.slice(start, end) - Copies a portion of the array and returnsReturn: Sends the data back to the position where it was called so it can be captured or used it
• arrayName.splice(start, deleteCount) - Cuts a portion of the array and returns it
• arrayName.splice(start, deleteCount, item1, item2, ...) - Cuts a portion of the array, returns it and then inserts new elements
• arrayName.concat(array2, ...) - Merges two or more arrays and returns a new array
• arrayName.join(separator) - Joins all elements of an array into a string, separated by the specified separator Separator: The string to separate each element from eachother in the resulting string. i.e. ", "

Gather info about arrays

• arrayName.length - Returns the number of values in the array
• Array.isArray(value) - Checks if the value is an array - the way this is written is a bit weird
• arrayName.indexOf(value) - Returns the index of the first occurrence of a value in the array
• arrayName.includes(value) - Checks if a value exists in the array

Conclusion/recap

Next: Recap