Migration to Smarty 5
Only if you already have an existing Smarty 3 project!
Where is Smarty 4?
For convenience, Smarty jumped from version 3 to version 5 (to be the same as Bootstrap)!
When Bootstrap 6 is released, Smarty 6 will come out! And so on!
So Bootstrap & Smarty versions are going in paralel!
Migration from Smarty 3
Javascript: fully compatible (Smarty 5 include jQuery)
CSS: partially compatible (see changelog for removed classes like .p--*, .m--*, etc)
Migration to Smarty 5 require html changes into your existing project.
Worth it? There are no really significant measurable improvements in Bootstrap 5 so there is no really need to migrate your project!
Bootstrap 4
.font-weight-*
.pl-
.pr-
.ml-
.mr-
.dropleft
.dropright
.text-left
.text-right
.float-left
.float-right
.border-left
.border-right
.no-gutters
.b-0, .b--0
.bl-0, .bl--0
.br-0, .br--0
.bt-0, .bt--0
.bb-0, .bb--0
.badge-primary
.badge-*
.sr-only
.h-*vh
.h-min-*vh
.form-label-group
data-target
data-toggle
data-dismiss
data-parent
data-original-title
data-backdrop
data-keyboard
data-trigger
data-container
data-content
data-placement
Bootstrap 5
fw-*
.ps-
.pe-
.ms-
.me-
.dropstart
.dropend
.text-start
.text-end
.float-start
.float-end
.border-start
.border-end
.g-0
.border-0
.border-start-0
.border-end-0
.border-top-0
.border-bottom-0
.bg-primary
.bg-*
.visually-hidden
.vh-*
.min-vh-*
.form-floating
data-bs-target
data-bs-toggle
data-bs-dismiss
data-bs-parent
data-bs-original-title
data-bs-backdrop
data-bs-keyboard
data-bs-trigger
data-bs-container
data-bs-content
data-bs-placement