JavaScript methods are actions that can be performed on objects. A JavaScript method is a property containing a function definition.
Here is some example of methods with input and output
var myArrray = new Array("el1", "el2","el3")
console.log(typeof(myArrray))
//object
var arr2 = ["l1","l2","l3"]
console.log(arr2.concat(myArrray))
//[ 'l1', 'l2', 'l3', 'el1', 'el2', 'el3' ]
var ar3 = new Array(2,4,'l',7,8,9)
console.log('Root: \n'+ ar3.map(Math.sqrt))
//Root: 1.4142135623730951,2,NaN,2.6457513110645907,2.8284271247461903,3
var ar4 = 'a,b,1,3,2,1'.split(',');
console.log(ar4.map(Math.sqrt))
//[ NaN, NaN, 1, 1.7320508075688772, 1.4142135623730951, 1 ]
console.log(ar3.join('*'))
//2*4*l*7*8*9
var ar5 = ['a','b','c','d']
ar5[ar5.length] = 'e'
console.log(ar5)
// [ 'a', 'b', 'c', 'd', 'e' ]