在 Javascript if-else 语句中包含“或”的多个条件

Question

I'm newbie in Javascript. Trying to write a function in which I will enter value for three items and it will return the total price. If I enter negative value for any parameter than it will give an error message instead of total price.

Expected results pseudocode:

if pen < 0 or pencil < 0 or sharpner < 0 then errorMessage else totalPrice

My code is:

function costCalc (pen, pencil, sharpner){

var penPrice = pen * 10;
var pencilPrice = pencil * 20;
var sharpnerPrice = sharpner * 5;

if (penPrice < 0 || pencilPrice < 0 || sharpnerPrice < 0 ){
    return "Something went wrong."
} else{
    var totalPrice = penPrice + pencilPrice + sharpnerPrice;
    return totalPrice
    }
}

I've 'return' twice here. Is this code ok? Or, I've to change something?

Advance thanks for your cooperation.

Regards.

Answer 1

Yes, what you are doing is fine. The moment you return from a function the remaining code is not executed, the function is "finished". In fact, it is very common to return from a function and intentionally skip the code after the return statement.

Answer 2

There is nothing wrong with your code but there are alternative ways of implementing it. A few examples, for your reference, could be:

/* 
 * `[item]Price` can be < 0 only if `[item]` < 0 so you can anticipate the check
 * in order to avoid unnecessary calculations
 */

function costCalcB(pen, pencil, sharpner) {
  if (pen < 0 || pencil < 0 || sharpner < 0) {
    return "Something went wrong."
  } else {
    const penPrice = pen * 10;
    const pencilPrice = pencil * 20;
    const sharpnerPrice = sharpner * 5;
    const totalPrice = penPrice + pencilPrice + sharpnerPrice;
    return totalPrice;
  }
}

/*
 * You can also avoid the `else` block
 */
 
 function costCalcC(pen, pencil, sharpner) {
  if (pen < 0 || pencil < 0 || sharpner < 0) {
    return "Something went wrong."
  }
  
  const penPrice = pen * 10;
  const pencilPrice = pencil * 20;
  const sharpnerPrice = sharpner * 5;
  const totalPrice = penPrice + pencilPrice + sharpnerPrice;
  return totalPrice;
}

/*
 * In case of error, you can also throw an exception rather than return
 */
 
 function costCalcD(pen, pencil, sharpner) {
  if (pen < 0 || pencil < 0 || sharpner < 0) {
    throw "Something went wrong."
  }
  
  const penPrice = pen * 10;
  const pencilPrice = pencil * 20;
  const sharpnerPrice = sharpner * 5;
  const totalPrice = penPrice + pencilPrice + sharpnerPrice;
  return totalPrice;
}

try {
    costCalcD(10, 10, -1);
} catch(e) {
    console.log(e);
}