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Javascript Articles
Page 350 of 534
Merge arrays in column wise to another array in JavaScript
Suppose, we have three arrays of numbers like these −const code = [123, 456, 789]; const year = [2013, 2014, 2015]; const period = [3, 4, 5];We are required to write a JavaScript function that takes in three such arrays. The function should then construct an array of objects based on these three arrays like this −const output = [ {"code": 123, "year": 2013, "period": 3}, {"code": 456, "year": 2014, "period": 4}, {"code": 789, "year": 2015, "period": 5} ];ExampleThe code for this will be −const code = [123, 456, 789]; const year = [2013, 2014, 2015]; const ...
Read MoreLoop through an index of an array to search for a certain letter in JavaScript
We are required to write a JavaScript function that takes in an array of strings as the first argument and a single character as the second argument.The function should return true if the character specified by second argument exists in any of the strings of the array, false otherwise.ExampleThe code for this will be −const arr = ['first', 'second', 'third', 'last']; const searchForLetter = (arr = [], letter = '') => { for(let i = 0; i < arr.length; i++){ const el = arr[i]; if(!el.includes(letter)){ continue; ...
Read MoreCount by unique key in JavaScript
Suppose, we have an array of objects like this −const arr = [ { assigned_user:{ name:'Paul', id: 34158 }, doc_status: "processed" }, { assigned_user:{ name:'Simon', id: 48569 }, doc_status: "processed" }, { assigned_user:{ name:'Simon', id: 48569 }, doc_status: "processed" } ];We are required ...
Read MoreCheck if user inputted string is in the array in JavaScript
We are required to write a JavaScript program that provides the user an input to enter a string value.The program should then check the input value against some hard-coded array values. Our program should print true to the screen if the input string value is included in the array, false otherwise.ExampleThe code for this will be − CHECK EXISTENCE const arr = ['arsenal', 'chelsea', 'everton', 'fulham', 'swansea']; const checkExistence = () => { const userInput = document.getElementById("input").value; const exists = arr.includes(userInput); document.getElementById('result').innerText = exists; }; Check OutputAnd the output on the screen will be −
Read MoreReduce an array to groups in JavaScript
Suppose, we have an array of strings that contains some duplicate entries like this −const arr = ['blue', 'blue', 'green', 'blue', 'yellow', 'yellow', 'green'];We are required to write a JavaScript function that takes in one such array. The function should merge all the duplicate entries with one another.Therefore, the output for the above input should look like this −const output = ['blueblue', 'green', 'blue', 'yellowyellow', 'green'];ExampleThe code for this will be −const arr = ['blue', 'blue', 'green', 'blue', 'yellow', 'yellow', 'green']; const combineDuplicate = (arr = []) => { let prev = null; const groups = arr.reduce((acc, value) ...
Read MoreFilter array of objects whose properties contains a value in JavaScript
Suppose, we have an array of objects like this −const arr = [{ name: 'Paul', country: 'Canada', }, { name: 'Lea', country: 'Italy', }, { name: 'John', country: 'Italy', }, ];We are required to devise a way to filter an array of objects depending on a string keyword. The search has to be made in any properties of the object.For instance −When we type "lea", we want to go through all the objects and all their properties to return the objects that contain "lea". When we type "italy", we want to go through all ...
Read MoreRemove duplicates and map an array in JavaScript
Suppose, we have an array of objects like this −const arr = [ {id:123, value:"value1", name:"Name1"}, {id:124, value:"value2", name:"Name1"}, {id:125, value:"value3", name:"Name2"}, {id:126, value:"value4", name:"Name2"} ];Note that some of the "name" property in objects within the array are duplicate.We are required to write a JavaScript function that takes in one such array of objects. The function should then construct a new array of strings that contains only unique "name" property value from the array.Therefore, the output for the above input should look like this −const output = ["Name1", "Name2"];ExampleThe code for this will be −const arr ...
Read MoreHow to group an array of objects by key in JavaScript
Suppose, we have an array of objects containing data about some cars like this −const arr = [ { 'make': 'audi', 'model': 'r8', 'year': '2012' }, { 'make': 'audi', 'model': 'rs5', 'year': '2013' }, { 'make': 'ford', 'model': 'mustang', 'year': '2012' }, { 'make': 'ford', 'model': 'fusion', 'year': '2015' }, { 'make': 'kia', ...
Read MoreFinding day of week from date (day, month, year) in JavaScript
We are required to write a JavaScript function that takes in three argument, namely:day, month and year. Based on these three inputs, our function should find the day of the week on that date.For example: If the inputs are −day = 15, month = 8, year = 1993OutputThen the output should be −const output = 'Sunday'ExampleThe code for this will be −const dayOfTheWeek = (day, month, year) => { // JS months start at 0 return dayOfTheWeekJS(day, month - 1, year); } function dayOfTheWeekJS(day, month, year) { const DAYS = [ 'Sunday', ...
Read MoreFinding the power of a string from a string with repeated letters in JavaScript
The power of the string is the maximum length of a non−empty substring that contains only one unique character.We are required to write a JavaScript function that takes in a string and returns its power.For example −const str = "abbcccddddeeeeedcba"Then the output should be 5, because the substring "eeeee" is of length 5 with the character 'e' only.ExampleThe code for this will be −const str = "abbcccddddeeeeedcba" const maxPower = (str = '') => { let power = 1 const sz = str.length - 1 for(let i = 0; i < sz; ++i) { ...
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