CODEWITHSUNDEEP
javascriptreactjs
Andrew Kim
Andrew Kim

Reputation: 3335

How can i use the return value of a function to be the return value of another function

I could be wording this a bit weird. Let me lay out some code to help explain. I'm writing a simple react component. This react component has a form where I submit a form. This is what I have so far:

onSubmit(event){
  event.preventDefault()
  if (this.checkQuantity()){
    // this is what i want to be simpler, the return value i want is already in the checkQuantity function in the if condition
    return true
  } else {
    let itemId = this.props.item.id
    let quantity = this.state.quantity
    this.props.onTransaction(itemId, quantity)
  }
}
checkQuantity(){
  if (this.state.quantity > this.props.item.quantity){
    alert("Can't buy what's not there!")
    return true
  } else {
    return false
  }
}

Like the comment states above, I just want the execution of the form submission to stop. I guess, I'm just looking for best practice in this type of situation. One where I'd like to abstract functionality but use the return value of that abstracted functionality in a conditional as a return.

Upvotes: 0

Views: 65

Answers (4)

Bergi
Bergi

Reputation: 664528

I'd write

onSubmit(event) {
  event.preventDefault()
  if (!this.checkQuantity()) {
    let itemId = this.props.item.id
    let quantity = this.state.quantity
    this.props.onTransaction(itemId, quantity)
  }
}
checkQuantity() {
  const isToomuch = this.state.quantity > this.props.item.quantity;
  if (isToomuch) {
    alert("Can't buy what's not there!")
  }
  return isToomuch
}

Or maybe you want to put the alert inside the onSubmit method, then checkQuantity becomes even simpler. Also you might want to rename checkQuantity to something more descriptive, like isInvalidQuantity.

Upvotes: 3

Anusha Dharmasena
Anusha Dharmasena

Reputation: 1269

I feel that you are splitting functions unnecessarily. Wouldn't the following code be enough?

onSubmit(event){
   event.preventDefault()
   if (this.state.quantity > this.props.item.quantity){
     alert("Can't buy what's not there!")
   } else {
     let itemId = this.props.item.id
     let quantity = this.state.quantity
     this.props.onTransaction(itemId, quantity)
   }
}

Also, like others mentioned, the return value has not significance in your example because you are not checking it.

Upvotes: 0

Chris Curnow
Chris Curnow

Reputation: 653

The problem here is you don't just want to return the value of checkQauntity(), you want to act on the return value and then decide what to do. In this case, the code you have is as good as any way of doing it.

But for a more general case (where you are not just returning true or false, you could do something like the following:

onSubmit(event){
 event.preventDefault();
 var check = checkQuantity();
 if (check > 6 ){
   return check;
 }
 else {
   //do something else..
 }
}

checkQuantity(){
 var someNumber = ...someNumber;
 return someNumber;
}

Upvotes: 0

Abdullah Ibn Farouk
Abdullah Ibn Farouk

Reputation: 133

onSubmit(event){
  event.preventDefault()
  return checkQuantity();
}
checkQuantity(){
  if (this.state.quantity > this.props.item.quantity){

alert("Can't buy what's not there!")
return true

  } else {

let itemId = this.props.item.id
let quantity = this.state.quantity
this.props.onTransaction(itemId, quantity)

return false

  }
}

Upvotes: 0

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