js for on object code example

Example 1: js loop through object

const obj = { a: 1, b: 2 };

Object.keys(obj).forEach(key => {
	console.log("key: ", key);
  	console.log("Value: ", obj[key]);
} );

Example 2: javascript loop through object

var obj = { first: "John", last: "Doe" };

Object.keys(obj).forEach(function(key) {
    console.log(key, obj[key]);
});

Example 3: javascript loop through object

Object.entries(obj).forEach(
    ([key, value]) => console.log(key, value)
);

// Loop using forEach
arr.forEach((item, index) => {
    // TODO
})

// Loop using for...of
for (const item of arr) {
    await something()
}

// Clone new array (not changing the old one)
const arr = [1,2,3]
const newArray = arr.map(item => item * 2)
console.log(newArray)

// Filter array by condition
const arr = [1,2,3,1]
const newArray = arr.filter(item => {
    if (item === 1) { return item }
})
console.log(newArray)

// Join array
const arr1 = [1,2,3]
const arr2 = [4,5,6]
const arr3 = [...arr1, ...arr2]
console.log(arr3)

// Get a property of object
const { email, address } = user
console.log(email, address)

// Copy object/array
const obj = { name: 'my name' }
const clone = { ...obj }
console.log(obj === clone)

Example 4: js for in object

var obj = { foo: 'bar', baz: 42 };
console.log(Object.entries(obj)); // [ ['foo', 'bar'], ['baz', 42] ]

for(const [i, val] of Object.entries(obj))
	new_obj[i] = val;

Example 5: for in object javascript

var obj = { foo: 'bar', baz: 42 };

Object.keys(obj).forEach((key) => {
    const el = obj[key];
    console.log(
      {
        key: key,
        value: el
      }
    );
});

Example 6: for in javascript

const object = {a: 1, b: 2, c: 3};

for (const property in object) {
  console.log(`${property}: ${object[property]}`);
}

// expected output:
// "a: 1"
// "b: 2"
// "c: 3"