No spaces between words when copying text

PDF files: 1.pdf 2.pdf 3.pdf

Configuration:

• Web browser and its version: Chrome, Firefox
• Operating system and its version: Ubuntu, macOS
• PDF.js version: 2.2.42, but the same was with 2.1.x, and with https://mozilla.github.io/pdf.js/web/viewer.html
• Is a browser extension: no

Steps to reproduce the problem:

1. Select text
2. Copy text

What went wrong?

Getting this: OpenSansisahumanistsansseriftypefacedesignedbySteveMatteson.OpenSanswasdesignedwithanuprightstress,openformsandaneu-tral,yetfriendlyappearance.Itwasoptimizedforprint,web,andmobileinterfaces,andhasexcellentlegibilitycharacteristicsinitsletterforms(seefigureonthefollowingpage).ThisfontisavailablefromtheGoogleFontDirectory[]asTrueTypefileslicensedundertheApacheLicenseversion‚.€.

Instead of this: Open Sans is a humanist sans serif typeface designed by Steve Matteson. Open Sans was designed with an upright stress, open forms and a neutral, yet friendly appearance. It was optimized for print, web, and mobile interfaces, and has excellent legibility characteristics in its letterforms (see figure 1 on the following page). This font is available from the Google Font Directory [1] as TrueType files licensed under the Apache License version 2.0.

This is quite significant problem, because I would say 1/20 of scientific papers encounter this problem.

[KnIfER]

how do chrome and acrobat handle this?

[FredBonux]

My “solution” above was based on this thought: If the distance is greater than the width of the narrower char of the font, then that distance should be a space. That’s because, usually, the " " is not the narrower char. But that is based on my “close to none” knowledge on fonts, hope it could help.