Arrays have many useful methods.
\n//How to create an array\nlet learningHowToCode = [\"stressed\", \"scared\", \"overwhelmed\", \"tired\"]A queue is one of the most common uses of an array. In computer science, this means an ordered collection of elements. Arrays in JavaScript can work both as a queue and as a stack. They allow you to add/remove elements both to/from the beginning or the end.
\nAccording to Wikipedia a double-ended queue (abbreviated to deque, pronounced deck[1]) is an abstract data type that generalizes a queue, for which elements can be added to or removed from either the front (head) or back (tail).
\npush method : adds elements to the end of the array
\nlet newJourney = learningHowToCode.push('Rewarding')pop method : removes the last element and returns that element only
\nlet mainGoal = learningHowToCode.pop('Rewarding')unshift : adds the element to the beginning of an array
\nlet focus = learningHowToCode.unshift('Takes time')shift : extracts the first element and returns it
\nlet reminder = learningHowToCode.shift('Takes time')var array = [1, 2, 3, 4, 5, 6]\nvar val = array[array.length - 1]splice : it can add, remove or replace elements.
\nSyntax:\narr.splice(index, deleteAmount, elem1,..anyOtherElement)\nHow to remove elements:
let poem = [\"high\",\"Still\", \"I'll\", \"Rise\"];\narr.splice(0, 1); // from index 1 (arrays are zero index based) remove 1 element\nconsole.log(poem); // [\"Still\", \"I'll\", \"Rise\"]How to add elements:
\nlet poem = [\"Still\", \"I'll\", \"Rise\"];\n// from index 0, delete 0, then insert \"by Maya Angelou\"\npoem.splice(0, 0, \"by Maya Angelou\");\nconsole.log(poem); // \"\"Still\", \"I'll\", \"Rise\", \"by Maya Angelou\"slice : returns a new array with a copy of elements that you specified (excluding the last element)
\nlet soup = [\"carrots\", \"onions\", \"garlic\", \"potatoes\", \"juice\"];\nconsole.log( soup.slice(0, 3) ); // \"carrots\", \"onions\", \"garlic\", \"potatoes\nconsole.log( soup.slice(-1) ); // juicelet days = [\"Monday\", \"Tuesday\"];\n// create a new array from: days and adds these new elements\nconsole.log( days.concat([\"Wednesday\", \"Thursday\"]) ); //\"Monday\", \"Tuesday\",\"Wednesday\", \"Thursday\"forEach : runs a function for each element in an array
\ndays.forEach(function(item){\nconsole.log(`Have a lovely day on ${item}!`)\n})\n//Have a lovely day on Monday!\n//Have a lovely day on Tuesday!names = [\"Leanne\", \"Sophie\", \"Max\", \"Jorge\", \"Peter\"]\nvar longNames = names.filter(function(name) {\n return name.length >= 6\n})\nconsole.log(\"Longer names: \", longNames)Find : Looks for an item, if found returns true, if not, returns false. Syntax:
\nlet result = arr.find(function(item, index, array) {\n//stops the loop if item is found and returns the item\n//item is the element. index is its index.\n});If we have an array of songs, and need to find the one with year == 2005
\nlet beyonceSongs = [\n{year: 2005, title: \"Check On It\"},\n{year: 2011, title: \"I Was Here\"},\n{year: 2011, title: \"Love On Top\"},\n{year: 2008, title: \"If I Were A Boy\"}, \n];\nlet oldestSong = beyonceSongs.find(song => song.year == 2005);\nconsole.log(oldestSong); // {year: 2005, title: \"Check On It\"}const tea = ['peppermint', 'chamomile', 'rooibos', 'earl grey'];\nconsole.log(tea.indexOf('rooibos')); // expected output: 2\nconsole.log(tea.indexOf('raspberry')); // expected output: -1map : One of the most popular methods. This method calls a function for each element of an array and returns an array of results. Syntax:
\nlet result = arr.map(function(item, index, array) {\n// returns the new value instead of item\n});For example, you can double each elements amount
\nlet wallet = [100, 250, 50, 5]\nvar newAmount= wallet.map(cash => cash * 2)\n//if you use it as a function, make sure you return\nconsole.log(newAmount)sort : sorts an array, and changes element order, the default sort order is ascending.\nThe items are sorted as strings by default.\nIf you want to use your own sorting order, you need to supply a function as the argument of arr.sort().\nmodifies the array
\nconst months = ['March', 'Jan', 'Feb', 'Dec'];\nmonths.sort();\nconsole.log(months);\n// expected output: Array [\"Dec\", \"Feb\", \"Jan\", \"March\"]I would recommend looking into the MDN docs for more information, their examples are the best.
\nreverse : reverses the order of elements in an array.\nmodifies the array
\nconst numbers = [1, 2, 3, 4, 5];\nconsole.log('reversed numbers:', numbers);reduce uses an \"accumulator\" whih basically means any value you want, the example used is a sum
\n[1, 2, 3].reduce(function(acc, n) { return acc + n; }, 0); // 6\n// Or written out:\nlet acc = 1;\nacc = acc + 2; // 3\nacc = acc + 3; // 6All in all, I do not have to go in depth with all the array methods because I can always refer to MDN Docs. Only gripe I have with it, is that I find it difficult to read sometimes. The words are either too technical or require more knowledge, with time it gets easier to read.
","excerpt":"Arrays have many useful methods. They are objects that are used to store lists of items. Elements inside can be of any data type, each one is accessed by it's…","frontmatter":{"date":"10 May, 2020","path":"/blog/arraymethods","title":"Array Methods"},"fields":{"readingTime":{"text":"6 min read"}}}},"pageContext":{}}}