for each loop on array code example

Example 1: For-each over an array in JavaScript

/** 1. Use forEach and related */
var a = ["a", "b", "c"];
a.forEach(function(entry) {
    console.log(entry);
});

/** 2. Use a simple for loop */
var index;
var a = ["a", "b", "c"];
for (index = 0; index < a.length; ++index) {
    console.log(a[index]);
}

/**3. Use for-in correctly*/
// `a` is a sparse array
var key;
var a = [];
a[0] = "a";
a[10] = "b";
a[10000] = "c";
for (key in a) {
    if (a.hasOwnProperty(key)  &&        // These checks are
        /^0$|^[1-9]\d*$/.test(key) &&    // explained
        key <= 4294967294                // below
        ) {
        console.log(a[key]);
    }
}

/** 4. Use for-of (use an iterator implicitly) (ES2015+) */
const a = ["a", "b", "c"];
for (const val of a) {
    console.log(val);
}

/** 5. Use an iterator explicitly (ES2015+) */
const a = ["a", "b", "c"];
const it = a.values();
let entry;
while (!(entry = it.next()).done) {
    console.log(entry.value);
}

Example 2: foreach in javascript

///Simple One
var a = ["a", "b", "c"];
a.forEach(function(entry) {
    console.log(entry);
});


///Function  concept

var fruits = ["apple", "orange", "cherry"];
fruits.forEach(myFunction);

function myFunction(item, index) {
  document.getElementById("demo").innerHTML += index + ":" + item + "<br>";
}

Example 3: perform a function on each element of array javascript

var new_array = old_array.map(function(e) { 
  e.data = e.data.split(','); 
  return e;
});