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How to evaluate condition in non short circuit way in typescript? Typescript does not allow & or | for boolean type. The reason why I need a non short circuit checking is I call showErrors in function isValueValid.

Given this function

function isValue1Valid(){
  if(value1 === 0) return true;    
  showErrors1();
  return false;
}

function isValue2Valid(){
  if(value2 === 0) return true;    
  showErrors2();
  return false;
}

Then in my condition

if(isValue2Valid() & isValue2Valid()){
//Submit data
}

Although I can do it like this one

if(isValue2Valid() & isValue2Valid()){
//Submit data 
   return;
}
showErrors1()
showErrors2()

But I feel to call it inside isValueValid function. In reality I always think to call show errors by default whenever there's an error.

How to evaluate condition in non short circuit way in typescript? Typescript does not allow & or | for boolean type. The reason why I need a non short circuit checking is I call showErrors in function isValueValid.

Given this function

function isValue1Valid(){
  if(value1 === 0) return true;    
  showErrors1();
  return false;
}

function isValue2Valid(){
  if(value2 === 0) return true;    
  showErrors2();
  return false;
}

Then in my condition

if(isValue2Valid() & isValue2Valid()){
//Submit data
}

Although I can do it like this one

if(isValue2Valid() & isValue2Valid()){
//Submit data 
   return;
}
showErrors1()
showErrors2()

But I feel to call it inside isValueValid function. In reality I always think to call show errors by default whenever there's an error.

• javascript
• typescript
• evaluation-strategy

Share Improve this question Follow edited Sep 21, 2016 at 9:57 jmvtrinidad asked Sep 21, 2016 at 9:28 jmvtrinidadjmvtrinidad 3,66855 gold badges2424 silver badges4242 bronze badges 10

• 7 To avoid an "XY Problem": why would you want to not short circuit? (I suspect you're dependent on side effects... if so extract those from the conditional expression.) – Richard Commented Sep 21, 2016 at 9:30
• Does sound indeed as an XY problem. Had that when I was staring up with programming when I thought I'd be clever and did something like if (process(otherStuff) && valid(stuff)) only to realise that it doesn't work if I swapped the conditions. – VLAZ Commented Sep 21, 2016 at 9:37
• I call some function inside something valid1() & valid2(). – jmvtrinidad Commented Sep 21, 2016 at 9:47
• 3 @janmvtrinidad you could just do what @Richard suggested, essentially var valid1 = isValue1Valid(); valid2 = isValue2Valid(); if (valid1 && valid2) although decoupling the validation logic from the error display might probably be better, so it would look like if (isValid()) { /* do stuff */ } else { /* display errors */ } – VLAZ Commented Sep 21, 2016 at 10:03
• 2 I think I would refactor to have the validation functions return a list of messages. If the list is empty then validation passed. So you end up with: var msgs = validation1(); msgs.concat(validation2()); if (msgs.length === 0) { return;}. – Richard Commented Sep 21, 2016 at 10:46

 |  Show 5 more ments

2 Answers 2

Sorted by: Reset to default 5

To answer your question, you could do

if ([isValue2Valid(), isValue2Valid()].every(Boolean)) {
    //Submit data
}

to evaluate all function calls and then bine their values. But you really shouldn't have isValueValid call showError in the first place. Instead, make your test functions return the error messages, and then if there are any, show them:

function getValue1Error() {
    if (value1 === 0) return null;
    else return "error1";
}

function getValue2Error() {
    if (value2 === 0) return null; 
    else return "error2";
}

// then:
const errors = [getValue1Error(), getValue2Error()] // or even better, just a loop over your fields
if (errors.some(Boolean)) {
    for (let error of errors)
        showError(error);
} else {
    // Submit data
}

If you want to use functions with side-effects (which is not a good idea in general), it might help to be very explicit about what is called and when:

   var value1Valid = isValue1Valid(); // might show some messages
   var value2Valid = isValue2Valid(); // might show some more messages

   if (value1Valid && value2Valid) {
        // submit data
   }

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