JavaScript Tutorial
indexjavascript history javascript versions environment setup variables and data typesOperatorsstrings and numbers programming constructs arrays built in objects functions objects call apply bind closures error handling debugging CallbacksJS in Browser
BOM and DOMBrowser EventsWeb APIAjaxJQueryMost popular librariesAdvanced
prototypes Object Oriented ProgrammingModulesAsynchronous programmingBinary DataInternationalizationreactangularjsProjectsMiscellaneous
typescriptJS ecosystemChrome dev toolstesting frameworksInterview questions and AnswersArrays in JavaScript
Important points to note about arrays are given below- Arrays are of reference types. (Non Primitives)
- Arrays can store numbers, strings, objects etc
- Multi dimensional arrays are supported in JavaScript
- Each array object supports the methods as defined in Array.prototype
- Arrays are passed by reference
Array definition Examples
//Array methods
let a = [2,3,'India']
console.log(a.toString()) // output - 2,3,India
//check if element exists
console.log(a.includes(2)) // output - true
//add element from the end
a.push(4)
console.log(a.toString()) // output - 2,3,India,4
a.push([4,5,6])
console.log(a.toString()) // output - 2,3,India,4,4,5,6
//remove element from the end
console.log(a.pop()) // output - [4,5,6]
console.log(a.toString()) // output - 2,3,India,4
a.shift();
console.log(a.toString()) // output - 3,India,4
a.unshift('65');
console.log(a.toString()) // output - 65,3,India,4
console.log(typeof a[1]) //number
a.splice(2,1)
console.log(a.toString()) // output - 65,3,4
let k = a.slice(0,1)
console.log(a.toString()) // output - 65,3,4
console.log(k.toString()) // output - 65
var emp = [
{ id: 20, name: 'USA' },
{ id: 24, name: 'UK' },
{ id: 56, name: 'Australia' },
{ id: 20, name: 'India' },
{ id: 88, name: 'Canada' }
];
console.log(emp.filter(e => e.id == 20) )
//output - [ { id: 20, name: 'USA' }, { id: 20, name: 'India' } ]
console.log(emp.map(e => e.name + 'new') )
//output - [ 'USAnew', 'UKnew', 'Australianew', 'Indianew', 'Canadanew' ]
console.log(emp.reduce((p,e) => p + e.id,0) ) //output - 208
console.log(emp.sort((a,b)=>a.id-b.id))
//output
/*
[ { id: 20, name: 'USA' },
{ id: 20, name: 'India' },
{ id: 24, name: 'UK' },
{ id: 56, name: 'Australia' },
{ id: 88, name: 'Canada' } ]
*/
console.log(emp.sort((a,b)=>b.id-a.id))
//output
/*
[ { id: 88, name: 'Canada' },
{ id: 56, name: 'Australia' },
{ id: 24, name: 'UK' },
{ id: 20, name: 'USA' },
{ id: 20, name: 'India' } ]
*/
console.log(Math.max.apply(null, emp.map(a=>a.id))) //output - 88
console.log(Math.min.apply(null, emp.map(a=>a.id))) // output - 20
//every, foreach, some, find, findIndex
a.forEach((v,i,a)=>
{console.log('inside for' + v);
})
// output
/*
inside for65
inside for3
inside for4
*/
Web development and Automation testing
solutions delivered!!