JavaScript function gives expected result in the console, but unable to assign result to a variable-CodePudding

I'm unable to assign the result of a function call to a variable.

Let's start with the following object:

let employees = [
    {
    id : 1,
    name : 'John Smith',
    age : 48,
    salary : 100000
    },

    {
    id : 2,
    name : 'Mary Jones',
    age : 29,
    salary : 78000,
    },

    {
    id : 3,
    name : 'Philip Lee',
    age : 36,
    salary : 160000,
    }
]

I have a function that accesses each employee's salary (except Mary) and applies a 20% increase:

function applySalaryIncrease(employees) {
    for (let i=0; i < employees.length; i  ) {
        if (i == 1){
            continue;
        }
        employees[i].salary = employees[i].salary * 1.2;
    }
 }

Next, I submit the following in the console:

applySalaryIncrease(employees)
employees

And, I see in the console that the salaries for John and Philip have increased, as expected.

However, when I assign the result to a variable named updatedEmployees, the result in the console is undefined.

updatedEmployees = applySalaryIncrease(employees)

Why is this happening?

Thanks! (JavaScript rookie here)

CodePudding user response：

Your function isn't returning anything explicitly, so it returns what JavaScript functions without an explicit return value deliver, which is undefined.

Fix it:

function applySalaryIncrease(employees) {
    for (let i=0; i < employees.length; i  ) {
        if (i == 1){
            continue;
        }
        employees[i].salary = employees[i].salary * 1.2;
    }
    return employees; // <-- explicitly return employees here
}

Usually it's not the best idea to mutate function arguments, so as long as all the array objects simply hold primitive data types, it's usually preferrable to create a shallow copy of the array passed:

function applySalaryIncrease(emps) {
    const employees = [...emps]; // this avoids mutating the array passed to the function
    for (let i=0; i < employees.length; i  ) {
        if (i == 1){
            continue;
        }
        employees[i].salary *= 1.2;
    }
    return employees; // <-- explicitly return employees here
}

CodePudding user response：

You are not returning any values so your variable gets undefined as a return from the function. However if you add a return employees before closing your function and after your loop it will return it.

Edit: I just saw it but it is exactly like the guy above me said