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Slightly re-factor how the BaseViewer/PDFThumbnailViewer handle page labels internally, to make the null default value clearer

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Currently it's not *immediately* clear from the code itself, unless you look at the definition of `this._pageLabels`, that the default value is `null`.[1]
We can improve this, and also reduce the amount of code, by using modern ECMAScript features such as optional chaining and nullish coalescing.

---
[1] Keep in mind that an *empty* string is actually a valid page label, according to the PDF specification.
This commit is contained in:
Jonas Jenwald 2021-02-05 16:24:39 +01:00
parent 094e0b2239
commit dc19965d78
2 changed files with 4 additions and 7 deletions
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8
web/base_viewer.js
View File

@ -290,7 +290,7 @@ class BaseViewer {
this.eventBus.dispatch("pagechanging", { this.eventBus.dispatch("pagechanging", {
source: this, source: this,
pageNumber: val, pageNumber: val,
pageLabel: this._pageLabels && this._pageLabels[val - 1], pageLabel: this._pageLabels?.[val - 1] ?? null,
previous, previous,
}); });
@ -305,7 +305,7 @@ class BaseViewer {
* labels exist. * labels exist.
*/ */
get currentPageLabel() { get currentPageLabel() {
return this._pageLabels && this._pageLabels[this._currentPageNumber - 1]; return this._pageLabels?.[this._currentPageNumber - 1] ?? null;
} }
/** /**
@ -631,9 +631,7 @@ class BaseViewer {
} }
// Update all the `PDFPageView` instances. // Update all the `PDFPageView` instances.
for (let i = 0, ii = this._pages.length; i < ii; i++) { for (let i = 0, ii = this._pages.length; i < ii; i++) {
const pageView = this._pages[i]; this._pages[i].setPageLabel(this._pageLabels?.[i] ?? null);
const label = this._pageLabels && this._pageLabels[i];
pageView.setPageLabel(label);
} }
} }

3
web/pdf_thumbnail_viewer.js
View File

@ -268,8 +268,7 @@ class PDFThumbnailViewer {
} }
// Update all the `PDFThumbnailView` instances. // Update all the `PDFThumbnailView` instances.
for (let i = 0, ii = this._thumbnails.length; i < ii; i++) { for (let i = 0, ii = this._thumbnails.length; i < ii; i++) {
const label = this._pageLabels && this._pageLabels[i]; this._thumbnails[i].setPageLabel(this._pageLabels?.[i] ?? null);
this._thumbnails[i].setPageLabel(label);
} }
} }