Depending on the type of code you are using there are a few possibilities. In general I find that the ISO 639 codes are used most of the time.
If you want to use those codes then the options would be the following
Spanish: es or spa
Basque: eu, eus or baq
Usually, in code (!) and not UI's, these are also used in combination with the ISO country code. For ...
Spanish could be ESP or SPA (find out which one is a better fit for your users).
Basque could be BAQ or EUS (make sure you select what the Basque population would recognise).
Important: I would use EUS short for Euskera only if the Basques recognise Euskera as Basque. Remember that you are providing
the language option for the Basque population not the ...
Usability testing is something that happens continuously and preferably starts before a single line of code is written. It is focused on testing the user experience of the (potential) product.
focused on behaviour, experience and goals.
starts before code is written and never ends
ranges from very inexpensive to very expensive
When you have too much content and little space, you should categorize your content and make a separate page for each content category. Besides, you need knowledge of an information architect. you can start card sorting or alternative options and categorize your content based on users minds.
If your users are too young to have email addresses, be careful about collecting any information such as phone numbers from them. Due to child protection laws like COPPA/GDPR, I would recommend verifying the legal requirements with a lawyer before making any decisions.
To your point about having a username without an email backup, this is often why apps ...
Short answer: yes. Which element, though depends on the content.
If a dialog contains the final step in a process that is not easily
reversible, such as deleting data or completing a financial
transaction, it may be advisable to set focus on the least destructive
action, especially if undoing the action is difficult or impossible.
You should test all colors within the same time frame. If you test sequentially, you reintroduce the "conflating variable of time", as Sam Blake explains in an answer to A/B Testing vs Cohort Analysis (emphasis added):
The point of doing A/B testing rather than cohort is that it eliminates the conflating variable of time. The data you gather is only valid ...