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JavaScript foreach
This article is written just to introduce you with Foreach loop and how you can efficiently use in different places. I hope you will able to understand it well and do let me know in the comment section if something is incorrect or can be added to make this post valuable.
ForEach() function is used to iterate through the items which can be array.
Array. (function(currentValue, index, arr), thisValue)
Here function is the callback function and currentValue is the element which is being processed, index is optional which meant to be the array index of the current element and arr is also option is the array object to which current element belongs to.
JavaScript array foreach
const numbers = [‘1234’, ‘2345’, ‘4563’, ‘4567’];
numbers.forEach((number, index, arr) => {
console.log(number,index, arr.length);
if(index+1==arr.length)
{
console.log(“Length of array is “+arr.length);
}
});
Output will be
1234 0 4
2345 1 4
4563 2 4
4567 3 4
Length of array is 4
JavaScript foreach example
function func() {
const items = [1, 2, 3];
const mult = [];
items.forEach(function(item){
mult.push(item*item);
});
document.write(mult);
}
func();
Output will be 1, 4, 9
In the above example each element in the array is multiplied to itself in block (item*item), 1×1, 2×2, 3×3 and then pushed to another array which is mult.
JavaScript foreach array of strings
const arraystring = [‘A’, ‘B’, ‘C’, ‘D’];
arraystring.forEach((letter, index, arr) => {
console.log(letter,index, arr);
});
Output will be
A0
(4) [ “A” ,”B” ,”C” ,”D” ]
B1
(4)[ “A” ,”B” ,”C” ,”D” ]
C2
(4)[ “A” ,”B” ,”C” ,”D” ]
D3
(4)[ “A” ,”B” ,”C” ,”D” ]
JavaScript foreach break
var Break = {};
const numbers = [‘1’, ‘2’, ‘3’, ‘4’];
try {
numbers.forEach(function(el) {
console.log(el);
if (el == 2) throw Break;
});
} catch (e) {
if (e !== Break) throw e;
}
Output will be
1
2
JavaScript foreach break Example
var Break = {};
const arraystring = [‘Dog’, ‘Cat’, ‘Cow’, ‘Horse’];
try {
arraystring.forEach(function(el) {
console.log(el);
if (el == ‘Cow’) throw Break;
});
} catch (e) {
if (e !== Break) throw e;
}
Output will be
Dog
Cat
Cow
JavaScript foreach continue
const arraycar = [‘BMW’, ‘Nissan’, ‘Ram’, ‘Audi’];
arraycar.forEach(function (car, index) {
// If the car is Ram, skip it
if (car === ‘Ram’) return;
// Otherwise log it to the console
console.log(car);
});
Output will be
BMW
Nissan
Audi
JavaScript foreach index
const checkindex = [‘A@S’, ‘XCD’, ‘ERF’, ‘DFG’];
checkindex.forEach(function (check, index) {
// If the word is ERF, check index
if (check === ‘ERF’)
{
console.log(check +” has index “+index);
}
});
Output will be ERF has index 2
JavaScript foreach index undefined
JavaScript foreach return
JavaScript foreach async
JavaScript foreach countdown
function countdown(number){
if (number < 1) {
return [];
} else {
const array = countdown(number – 1);
array.unshift(number);
return array;
}
}
console.log(countdown(6));
Output
(6)[,6 ,5 ,4 ,3 ,2 ,1] will be
JavaScript foreach order
const letters = [‘C’,’A’,’B’,’D’, ‘2’, ‘1’];
letters.sort();
console.log(letters)
(6)[ “1” ,”2″ ,”A” ,”B” ,”C” ,”D” ]
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