PHP stalled in pre-6.0 land and then jumped straight to 7.0 because the release was just not going to happen. The closest thing in Node I can think of is ES4 (which failed, resulting in a jump to 5 and ActionScript diverging further).
Node stalled in pre-1.0 land with what was effectively a feature freeze before io.js split off and jumped to 1.0. Io then went on a regular release schedule strictly following semver leading to 2.0 and then 3.0. These aren't backwards incompatible in the sense that PHP 5 is to 4 or Python 3 is to 2 -- most code will likely still work; they mostly propagated breaking changes caused by updates to the underlying V8 engine, breaking some native extensions. The "jump" from 0.12 to 4.0 for Node is because instead of merging io.js back into Node, Node 0.12 was merged into io.js and io.js became the new Node 4.
PHP stalled in pre-6.0 land and then jumped straight to 7.0 because the release was just not going to happen. The closest thing in Node I can think of is ES4 (which failed, resulting in a jump to 5 and ActionScript diverging further).
Node stalled in pre-1.0 land with what was effectively a feature freeze before io.js split off and jumped to 1.0. Io then went on a regular release schedule strictly following semver leading to 2.0 and then 3.0. These aren't backwards incompatible in the sense that PHP 5 is to 4 or Python 3 is to 2 -- most code will likely still work; they mostly propagated breaking changes caused by updates to the underlying V8 engine, breaking some native extensions. The "jump" from 0.12 to 4.0 for Node is because instead of merging io.js back into Node, Node 0.12 was merged into io.js and io.js became the new Node 4.