forEach()

 

 

 forEach(callbackfn: (value: T, index: number, array: T[]) => void, thisArg?: any): void;

Performs the specified action for each element in an array.

 

@param callbackfn A function that accepts up to three arguments.

forEach calls the callbackfn function one time for each element in the array.

 

@param thisArg An object to which the this keyword can refer in the callbackfn function.

If thisArg is omitted, undefined is used as the this value.

 

 

 

example.

1. 

let numbers = [1, 2, 3, 4, 5, 6, 7];

numbers.forEach(function(num) {
  console.log(num);
})

// same code
numbers.forEach(num => console.log(num));

 

 

2.

let fruits2 = ['🍎','🍒','🍌','🍉','🍓'];
let fruits3 = ['🥝'];

fruits2.forEach(fruit => fruits3.push(fruit));
console.log(fruits3);
// [ '🥝', '🍎', '🍒', '🍌', '🍉', '🍓' ]

 

 

3. 

let sum = 0;
let numbers2 = [20, 11, 33, 10, 7, 77];

numbers2.forEach(addTotal);

function addTotal(num){
  sum += num;
}
console.log(sum);
// 158

// same code
numbers2.forEach(number => sum += number)
console.log(sum);
// 158

 

 

4.

let number3 = [20, 11, 33, 10, 7, 77, 5];
number3.forEach((number, index, array) => {
  array[index] = number * 2;
})

console.log(number3);
// [40, 22, 66, 20, 14, 154, 10]