refactor(landing): refine the labels param parsing logic

[tawera-manaena]

Motivation

While looking through the basemaps/landing package, I noticed that the code for handling the labels URL query parameter is hard to understand. The default behavior is also unclear. This work aims to fix that.

• Refactors code from feat(landing): enable labels upon first visit BM-1101 #3364

Modifications

1. Modified the code responsible for parsing the labels URL query parameter. The code lives within the updateFromUrl function. A 'before' and 'after' is as follows:

   Before

   The current logic, although concise, is a little difficult to interpret:

   if (labels == null) {
     this.labels = layerId === "aerial" && this.isDebug === false;
   } else {
     this.labels = labels !== "false";
   }

   After

   The updated logic, although verbose, seeks to clarify the process flow and explain each statement's context:

   this.labels = false;
   
   if (typeof labels === "string") {
     // enable labels for any string value other than "false"
     if (labels !== "false") this.labels = true;
   } else {
     // if not in debug mode, show labels for the aerial layer by default
     if (layerId === "aerial" && !this.isDebug) this.labels = true;
   }

2. Expanded upon some of the existing test cases that validate the parsing logic for the labels URL query parameter.

Verification

All of the original and adjusted test cases pass, indicating that the parsing logic remains unchanged.

[blacha]

the typing for .get is URLSearchParam.get(name: string): string | null; so it can only ever be a string or null,

so labels == null is clearer to me over typeof

For example:

new URLSearchParameters('x=1').get('x') // '1'

[blacha]

We generally try and avoid !foo as that triggers type cohersion causing you to think of all the horrible values that javascript would consider to be truthy.

We generally try to be as explicit as possible, so this.isDebug === false would be my preference

[tawera-manaena]

Refactor: Post-Feedback

I'll park this for now. Will revisit this soon.

this.labels = false;

if (labels == null) {
  // if not in debug mode, enable labels for the aerial layer by default
  if (this.isDebug === false && layerId === "aerial") this.labels = true;
} else {
  // enable labels for any value other than "false"
  if (labels !== "false") this.labels = true;
}