".pragma library" statement in JavaScript breaks lupdate

We have UI strings in JavaScript library files need localization, but seems lupdate (4.7.1) fails to parse the .js library file - it reports error line number of the line ".pragma library" and skips the rest content.

For example, running lupdate on loclib.js which has only 3 lines code:

.pragma library
function locstring()

The output from lupdate is as below and nothing added to loclib.ts.

C:\Temp>lupdate loclib.js -ts loclib.ts
C:/Temp/loclib.js:1:
Updating 'loclib.ts'...
Found 0 source text(s) (0 new and 0 already existing)

If comment out ".pragma library" , lupdate will find the qsTr("logicalNameHere").