JS5 ClassNotes (1) PDF

Functions in JS Block of code that performs a specific task, can be invoked whenever needed lege Col pna A Functions in JS Function Definition Function Call function fu...

Functions in JS Block of code that performs a specific task, can be invoked whenever needed lege Col pna A Functions in JS Function Definition Function Call function functionName( ) { functionName( ); //do some work lege } Col pna A function functionName( param1, param2...) { //do some work } Arrow Functions ge Compact way of writing a function olle a C const functionName = ( param1, param2...) => { } //do some work Apn const sum = ( a, b ) => { return a + b; } Let‘s Practice Qs. Create a function using the “function” keyword that takes a String as an argument & returns the number of vowels in the string. lege Col na Qs. Create an arrow function to perform the same task. Ap forEach Loop in Arrays arr.forEach( callBackFunction ) CallbackFunction : Here, it is a function to execute for each element in the array lege l *A callback is a function passed as an argument to another function. a Co arr.forEach( ( val ) => { console.log(val); Ap n }) Let‘s Practice Qs. For a given array of numbers, print the square of each value using the forEach loop. lege Col pna A Some More Array Methods Map Creates a new array with the results of some operation. The value its callback returns are used to form new array lege Col a arr.map( callbackFnx( value, index, array ) ) Ap let newArr = arr.map( ( val ) => { n return val * 2; }) Some More Array Methods Filter Creates a new array of elements that give true for a condition/filter. ge Eg: all even elements olle let newArr = arr.filter( ( ( val ) => { na C }) return val % 2 === 0; Ap Some More Array Methods Reduce lege Col Performs some operations & reduces the array to a single value. It returns na that single value. Ap Let‘s Practice Qs. We are given array of marks of students. Filter our of the marks of students that scored 90+. lege Col na Qs. Take a number n as input from user. Create an array of numbers from 1 to n. p A Use the reduce method to calculate sum of all numbers in the array. Use the reduce method to calculate product of all numbers in the array.