QLT.10.01 Mid-level

i18n fundamentals + RTL, scripts and fonts

Comes up in: Frontend system design, Web fundamentals

This concept is being written. It gets the full five steps — explanation, predict, interview angle, practice with tests, and review cards. Here is exactly what it will cover, so you can study it elsewhere in the meantime.

What it covers

externalising strings
ICU message format (plurals, select)
Intl APIs
locale negotiation
number/date/currency formats (lakh/crore grouping in en-IN)
text expansion
libraries (FormatJS, i18next)
dir and logical CSS properties
bidi text
Indic script shaping and line breaking
font fallbacks
sorting with Intl.Collator

Words you will know

i18nl10nlocaleICU message formatpluralisationRTLbidilogical property

What you will practise

localise a page into Hindi and German
make a layout RTL-ready

Interview questions this answers

How would you add internationalisation to an existing React app?
Why is string concatenation bad for translations?
How do you support right-to-left languages?
How do number formats differ between en-US and en-IN?