This study explores writing in an Internet environment from a translanguaging perspective. Through the analysis of screen recordings, stimulated recalls and interviews, the study reveals 12 Chinese EFL undergraduates' engagement with four specific cognitive processes: source searching, evaluation, reading and integration. It also identifies their flexible deployment of three types of translanguaging strategies: prior-knowledge-based, linguistic and digital strategies. The study connects the cognitive-socio-cultural sphere of L2 source-based writing processes, highlighting the importance of both cognitive processes and sociocultural resources. It offers insights into emerging features of writing in online environments. This contributes to redefining writing and writing ability in the digital age and to reshaping pedagogical practices for effective use and integration of resources in both L1 and L2 writing.