map() and forEach()

Callback Function
A callback function is a function that is passed as an argument to another function and executed later.

<script>
    function mainFun(callback){
        console.log("main function executed");
         callback()
    }

    function callback(){
        console.log("callback function executed");
    }
    mainFun(callback)

</script>

Output:main function executed
callback function executed

forEach()
The forEach() method calls a function (a callback function) for each array element
It does not return a new array or alter the original array, making it useful for operations like logging or modifying elements in place

Syntax

array.forEach(function(currentValue, index, array) {
    // action
});

let fruits=["apple","orange","mango","banana"]
fruits.forEach(fru)

function fru(i,j,k){
    console.log("Fruits are Healthy",i,j,k)
}

Output:Fruits are Healthy apple 0 [ 'apple', 'orange', 'mango', 'banana' ]
Fruits are Healthy orange 1 [ 'apple', 'orange', 'mango', 'banana' ]
Fruits are Healthy mango 2 ['apple', 'orange', 'mango', 'banana' ]
Fruits are Healthy banana 3 [ 'apple', 'orange', 'mango', 'banana' ]

let fruits=["apple","orange","mango","banana"]
fruits.forEach((fru)=>{
    console.log(fru.toUpperCase())
})

Output:APPLE
ORANGE
MANGO
BANANA

let fruits=["apple","orange","mango","banana"]
let fru=fruits.forEach((f)=>{
    return f.toUpperCase()
})
console.log(fru);

Output:undefined

map()
It creates a new array by applying a specified function to each element of the original array
It returns a new array with the transformed values, leaving the original array unchanged

Syntax

array.map(function(currentValue, index, array) {
    return newValue;
});

let fruits=["apple","orange","mango","banana"]
let fru=fruits.map((f)=>{
    return f.toUpperCase()
})
console.log(fru);

Output:[ 'APPLE', 'ORANGE', 'MANGO', 'BANANA' ]

let fruits=["apple","orange","mango","banana"]
fruits.map((fru)=>{
    console.log(fru.toUpperCase())
})

Output:APPLE
ORANGE
MANGO
BANANA

Difference between map() and forEach()