how to change array element in javascript code example

Example 1: replace array element javascript

// Replace 1 array element at index with item 
arr.splice(index,1,item);

Example 2: modify array elements javascript

Using a FOR loop, write a function addNumber which adds the argument n to each 
number in the array arr and returns the updated arr:
const addNumber=(arr, n)=>{  
  let arr1=[];
  for(let i=0;i<Math.max(arr.length);i++){
    arr1.push((arr[i]||0)+n)
  }
  return arr1;
} 
console.log(addNumber([4, 5, 6], 7)); // expected log [11, 12, 13]

Example 3: modify array js

let newArray = oldArray.map(funcToEachElem);

Example 4: js array modify element

people[0] = "Georgie";