vim folding collapse

If you have code like

function name {

  line 1

  line 2

  line 3

}

Manual Collapsing (fall in)

1. Move the cursor to initial {
2. Press zf%

Manual Decollapsing (fall out)

1. Move the cursor to collapsed line
2. Press SHIFT + zf%

How to fold text in a JSON file?

:set filetype=json

:syntax on

:set foldmethod=syntax 

References

More info at https://makandracards.com/gmitrev/4513-vim-cheatsheet