```js const arr = [1,2,3,4]; ``` [[arr.at]] `arr.at(1)` Takes an integer value and returns the item at that index [[arr.concat]] `arr.concat(arr2)` Returns new array joining arr and arr2 together [[arr.every]] `arr.every(fn)` Returns true if all elements in arr pass the test in fn [[arr.fill]] `arr.fill(val, start, end)` Changes all elements in range to a the specified value [[arr.filter]] `arr.filter(fn)` Returns new array with all elements that pass the test implemented by the provided function. [[arr.flat]] `arr.flat()` Returns array with subarrays concatenated up to the specified depth [[arr.flatMap]] `arr.flatmap()` Same as .map() with a successive flat() [[arr.forEach]] `arr.forEach(fn)` Calls function `fn` for each element in the array [[arr.findIndex]] `arr.findIndex()` Returns index of first element that satisfies the callback function condition [[arr.IndexOf]] `arr.indexOf(1)` Returns index of first occurence of element in arr [[Array.isArray]] `Array.isArray(arr)` Returns true if arr is an array [[arr.join]] `arr.join(',')` Joins all elements into a string separated by separator [[arr.lastIndexOf]] `arr.lastIndexOf(obj)` Returns index of last occurence of element in arr [[arr.length]] `arr.length` Returns length of arr [[arr.map]] `arr.map(fn)` Returns new array with the results of running fn on every element [[arr.pop]] `arr.pop()` Removes and returns last element from arr [[arr.push]] arr.push(5) // Adds element to end of arr and return new length [[arr.reduce]] `arr.reduce(fn)` Returns a single value which is the function's accumulated result L2R [[arr.reduceRight]] `arr.reduceRight(fn)` Returns a single value which is the function's accumulated result R2L [[arr.reverse]] `arr.reverse()` Reverse order of arr [[arr.shift]] `arr.shift()` Removes and returns first element from arr [[arr.slice]] `arr.slice(start, end)` Returns a section of arr from start to end (end non-inclusive) [[arr.some]] `arr.some(fn)` Returns true if at least one element in arr passes the test in fn [[arr.sort]] `arr.sort` Sort the elements of arr [[arr.splice]] `arr.splice(start, count, val)` Changes content of arr removing, replacing, and adding elements [[str.split]] turns a string into an array [[arr.toString]] `arr.toString()` Returns a string representing arr its elements (same as `arr.join(',')`) [[arr.unshift]] `arr.unshift(0)` Adds element to start of arr and return new length ___ **Tags**: #arrayMethods