Clear subform Lookup field when another subform lookup field is changed (on the same row)

[incoherence]

I have a subform with two Lookup fields, let's call them LOOKUP_A and LOOKUP_B
When the user changes the (looked up) value in LOOKUP_A, I want to clear (i.e. set to blank) LOOKUP_B on the same row.
I would like to do this in JavaScript if possible.
I am struggling with this simple task - any help appreciated... thanks!

[kev1n]

Hi,

Add this JS in the LOOKUP_A's LUJS event:

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	  const sfId = 'sf_id'; // subform object id
	  const lookupB = 'id_lookup'; // LOOKUP_B id

	  objLookupB = $('#' + sfId + nuPad3(nuSubformRow) + lookupB);
	  if (!objLookupB.value) {
	      nuGetLookupId(null, objLookupB.attr('id'), false, false);
	  }

If LOOKUP_B also needs to be cleared when LOOKUP_A is cleared, you'll need to add an onchange event as well.

[incoherence]

I am not sure how it works exactly, but it does! Thanks so much, Kevin!

> const sfId = 'sf_id'; // subform object id
> const lookupB = 'id_lookup'; // LOOKUP_B id
> objLookupB = $('#' + sfId + nuPad3(nuSubformRow) + lookupB);

Here, is "nuSubformRow" a kind of "built-in" global variable that contains the (zero-based) subform row number?

I couldn't find nuPad3() but looks like it pads an integer to make it three digits (with leading zeros if required).

> if (!objLookupB.value) {

What is the purpose of this conditional, please?

(I think I need to go and read up more about jQuery to understand how the rest of the code works)

[kev1n]

I couldn't find nuPad3() but looks like it pads an integer to make it three digits (with leading zeros if required).

Correct.

> if (!objLookupB.value) {

What is the purpose of this conditional, please?

! Is the logical NOT operator:

https://developer.mozilla.org/en-US/doc ... ogical_NOT

E.g. this

Code: Select all

! objLookupB.value

is the same as

Code: Select all

objLookupB.value != '' || objLookupB.value !== undefined || objLookupB.value !== null

The if statement checks if objLookupB.value is falsy (i.e., if it is null, undefined, 0, NaN, or an empty string). If objLookupB.value is not falsy, the code block inside the if statement is executed.