JavaScript jump to label

March 31, 2023

I’m trying to make a function that validates user input and return true if there are no mistakes or false (and display a message) if there is a problem.

If an error found, there is no need to check other inputs, just jump to the end of the function to set and format the error

let ValidateInput = function() {

  let errorMessage = "";

  if (input1 == "") {
    errorMessage = "Something";
    continue exithere;
  }

  if (input2 == "") {
    errorMessage = "Something else";
    continue exithere;
  }

  exithere:
  if (errorMessage != "") {
    //Display error
    //Change error <p>'s format by adding classlist
  }
}

Using continue or break shows the error "Jump target cannot cross function boundary .ts(1107)", but my label (exithere:) is inside the function…

I know I can use "return false;" at the end of each if, but I prefer to have only 1 exit point from my function where I can display and format the message just one time, and not at the end of each if statement.

Using break ended with the same error.

>Solution :

You could wrap the whole block of code in a do...while that executes only once and use break to go to the end. But this is much less readable than just returning on invalid input.

let errorMessage = "";
do {
  if (input1 == "") {
    errorMessage = "Something";
    break;
  }

  if (input2 == "") {
    errorMessage = "Something else";
    break;
  }
} while (0);
// break goes to here