js_of_ocaml: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/js_of_ocaml - from package: js-of-ocaml

You may install the required package with command apt-get install {package}

Error in other languages:
js_of_ocaml: bevel nie gevind nie
js_of_ocaml: comandă negăsită
js_of_ocaml: comando não encontrado
js_of_ocaml: commande introuvable
js_of_ocaml: command not found
js_of_ocaml: käsku ei ole
js_of_ocaml: không tìm thấy lệnh
js_of_ocaml: komanda nerasta
js_of_ocaml: Kommando nicht gefunden.
js_of_ocaml: kommandot finns inte
js_of_ocaml: komut yok
js_of_ocaml: nie znaleziono polecenia
js_of_ocaml: níor aimsíodh an t-ordú
js_of_ocaml: no se encontró la orden
js_of_ocaml: no s'ha trobat l'ordre
js_of_ocaml: opdracht niet gevonden
js_of_ocaml: parancs nem található
js_of_ocaml: perintah tidak ditemukan
js_of_ocaml: príkaz nenájdený
js_of_ocaml: příkaz nenalezen
js_of_ocaml: команда не найдена
js_of_ocaml: командата не е открита
js_of_ocaml: 命令找不到
js_of_ocaml: コマンドが見つかりません