Convert conditional statement to variable in Javascript

Question

I have the following code which I use in various places

  if(!value[field]){
    errors[field] = `${FIELDS[field].errorMessage}`;    
  }

Is it possible to set this as a variable in javascript?

I thought of putting this as a property of an object and calling it from there. Below is my code

   _.each(FIELDS, (type, field) => {
     if (FIELDS[field].validate) {
       if (!value[field]) {
         errors[field] = `${FIELDS[field].errorMessage}`;
       }

       switch (FIELDS[field].formType) {
         case "email":
           if (!/^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}$/i.test(value.email)) {
             errors.email = 'Invalid email address'
           }
         default:
           if (!value[field]) {
             errors[field] = `${FIELDS[field].errorMessage}`;
           }
       }
     }
   });
   return errors;
}

Can you add complete code with demo. minimal reproducible example — Tushar
– Tushar, Commented May 5, 2016 at 4:58
Set what as a variable? Variables do not contain code. Do you mean define it as a function which you can call from "various places"? — user663031
– user663031, Commented May 5, 2016 at 5:01
@torazaburo Yes, I was thinking to do something like this var check = { func : (function(){...;})() }; but was wondering if there were other methods — lost9123193
– lost9123193, Commented May 5, 2016 at 5:04
You mean like var isNotPresent = !value[field]; and then call it like if(isNotPresent){...} ? is that what you mean? — blurfus
– blurfus, Commented May 5, 2016 at 5:06

Avindu Hewa · Accepted Answer · 2016-05-05 07:17:20Z

2

One thing you could probably try is saving this as a string to a variable and running eval when you need , but it might be a bit slow and issues might come up if your program is asynchronous

var condition ="if(!value[field]){errors[field]=`${FIELDS[field].errorMessage}`;}"

and then just run eval(condition) for where ever you want it

for(var x = 0 ; eval(condition);x++){}

answered May 5, 2016 at 7:17

Avindu Hewa

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Comments

user663031 · Accepted Answer · 2016-05-05 05:10:35Z

0

Define a function setError:

function setError() {
  if(!value[field]) {
    errors[field] = `${FIELDS[field].errorMessage}`;    
  }
}

Place this inside the arrow function you are passing to _.each.

Then each place you want to use it just invoke it:

setError();

That's what functions are for.

However, as your code stands, you are executing this twice, once at the top, and another time inside the default case. Why are you doing that?

answered May 5, 2016 at 5:10

user663031

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