Tips for verifying if a field is empty with javascript

Question

Tips for verifying if a field is empty with javascript

I am trying to use JavaScript to determine if a field is empty.

Here is the scenario: If the result.title field is not available or empty, I need to display a default title.

These are the conditions:

- If the result.title is available, show that as the title.
- If result.title is empty and name is present, show the string "${name} matches".
- If result.title is empty and name is not present, show the string "default title".

This is what I have attempted so far:

const defaultTitle = result?.title ?? "default title";

However, this does not account for an empty title field and whether the name is present or not.

Can someone please assist me with this? Thank you.

Thank you!

javascript

Answer 1

Answer №1

To determine if a string is empty (meaning undefined, null, or "") you can use the following code:

!str || str === ''

Here, the variable str represents a value that could be undefined, null, or a string.

In this scenario, I have altered the logic to check for the presence of a string rather than its emptiness, based on the context provided in your example.

const is_present = (str) => str && str !== '';

const get_title = (title, name) =>
  is_present(title) ? title :
  is_present(name)  ? name + ' matches' :
    'default title';

console.log("null, 'Foo':      " + get_title(null, 'Foo'));
console.log("'Bar', 'Foo':     " + get_title('Bar', 'Foo'));
console.log("'Bar', null:      " + get_title('Bar', null));
console.log("'', 'Foo':        " + get_title('', 'Foo'));
console.log("'', '':           " + get_title('', ''));
console.log("{}?.title, 'Foo': " + get_title({}?.title, 'Foo'));

Answer 2

To determine if a string is empty (meaning undefined, null, or "") you can use the following code:

!str || str === ''

Here, the variable str represents a value that could be undefined, null, or a string.

In this scenario, I have altered the logic to check for the presence of a string rather than its emptiness, based on the context provided in your example.

const is_present = (str) => str && str !== '';

const get_title = (title, name) =>
  is_present(title) ? title :
  is_present(name)  ? name + ' matches' :
    'default title';

console.log("null, 'Foo':      " + get_title(null, 'Foo'));
console.log("'Bar', 'Foo':     " + get_title('Bar', 'Foo'));
console.log("'Bar', null:      " + get_title('Bar', null));
console.log("'', 'Foo':        " + get_title('', 'Foo'));
console.log("'', '':           " + get_title('', ''));
console.log("{}?.title, 'Foo': " + get_title({}?.title, 'Foo'));

Tips for verifying if a field is empty with javascript

Answer №1

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