What is the best way to implement content substitution (multi-landing) on ​​a PHP or JavaScript site?

Question

PHP

Specialists and gurus! Prompt on what would be better, more correctly to fasten content substitution to lp, to JS or PHP? Feel free to justify your answers =)

Answer 1

I choose php, if I use js, then some time passes before the content is replaced and the visitor can see it. This can scare him away.