JavaScript Tutorial
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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
*/
Complex problems, Simple Solutions