Javascript - pass by sharing

如果用.push等操作，會影響原始值；如果是直接賦予新值，不會影響原始值
1.

function modifyArray(arr) {
  arr.push(4)
}

let myArray = [1, 2, 3]
modifyArray(myArray)
console.log(myArray) // [1, 2, 3, 4]

2.

function modifyArray(arr) {
  arr = [1, 2, 3, 4]
}

let myArray = [1, 2, 3]
modifyArray(myArray)
console.log(myArray) // [1, 2, 3]