Architecture · 2005–now · Web Boom
Ajax SPAs (early)
Partial page updates without full reloads. Became the mental model for every modern front-end framework.
How Ajax SPAs (early) mutated
Ajax mutated the web from document navigation to application state — then frameworks industrialized the pattern. The fad layer was calling every page an app. The durable win was asynchronous partial updates, now table stakes.
Case studies

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Related
Framework · 2006–2018
jQuery
DOM peace treaty for a fractured browser world. Mission accomplished — then frameworks ate its job.
Framework · 2013–now
React
Components and unidirectional data. Won the front-end by being good enough and having a gravitational ecosystem.
Architecture · 2004–now
MVC web frameworks
Model-view-controller as the default web shape. Still how most server-rendered apps think.