more on funcs, arrays,bind,CB, forEach,map(),filter,reduce,DOM

Question 1

how can i bind a param to a func? and wha t is the point of binding a func?

Answer 1

create a funcparam
now create a binded func:
let bound = OGfuncName.bind(null, prevalent value)

note: i set null because in this case the “this” keyword isnt used
2. binding a func is usefull if a have a certain param that is used frequently!

basically im creating a new func just for a special param

Question 2

provide an example on a CB func that acts like a bind func.

Answer 2

1. create an OGfunc with a param
2. return the CB with a parm
3. RETURN the expression
4. berryup the OGfunc with a param
5. func the berry and paramize it; then call it

const taxRater = function (rate) {
  return function (value) {
    return value * rate + value; }; };

const getTax = taxRater(0.1);
console.log(getTax(200));

Question 3

how can bind be useful with objts? describe an example.

Answer 3

Bind can be useful if a have abunch of objts that require the same method:

const myMethod = ogMethod.bind(otherObj)
myMethod( otherParam, otherParam1)

NOTE: Console.log(otherOBJ) to see the results

Question 4

Why is bind useful with eventHandlers? describe what an event handler function loos like?

Answer 4

the handler func “this” keyword always points to the html element, not the obj we want.
Fix:
document.querySelector(‘btn-name’).addEventListener(‘click’, obj.method.bind( obj )

Question 5

arr = [1,2,3,4,5]
what does: arr.splice(1, 2) prnt?

why is slice cool?

Answer 5

[1, 4, 5]

It is good for deleting unwanted items. especially the last item

Question 6

how can i get the last item of an array?

can i use at with strs?

Answer 6

arr. at( -1 )

yessir: CL(‘jonas’.at( 0 )

Question 7

what old fashion method does the forEach() replace?

give an example please.

Answer 7

it replaces the for loop if/else block.

let x = array.forEach(function(item, i, array) {
        return (expression) } )

Question 8

How can i upload a list child element to a webpage?

Answer 8

(container name) which is…..

doc.QS-tag berry.insertAdjacentHTML(‘afterbegin’, htmlStringBerry)

Question 9

How can i delete container elements from a webpage?

Answer 9

container name.innerHTML = ‘ ‘;

Question 10

What does map( ) do? Provide an example.

Answer 10

map method creates a new array with items that have undergone an operation. Its a CB func.

const newArr = oldArr.map(function(item, i, array) {
        return item * usdToEuroBerry} )

this returns a new array with all items updated according to the operation specified.

Question 11

what does filter do? Example plz.

Answer 11

filter method revises an array based on a condition

const positiveNums = +&-Array.filter(function(item, i ) {
       return item > 0 } )

Question 12

describe the “creating a username forEach method” that jonas taught you.

we are cycling an array of objs and adding a prop to each obj in the array

Answer 12

const createUser = function(accs) {

accs. forEach(function(acc ) {
     accs. username = accs.owner.toLowerCase( ).split(' ').map( name => name[ 0 ].join()

createUser( arrayOfaccountObjs)

Question 13

what does the reduce method do? example plz

Answer 13

reduce method boils all items in an array down to one value via the snowball accumulator:

const x = array.reduce(function(acc, item, i, array) {
    return acc + cur}, 0 );

this gives the sum of all numbers. NOTE: remember the accumulator start point parameter