uglifyjs: 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 CentOS possible default full paths are:

/usr/lib/node_modules/uglify-js@1/bin/uglifyjs - from package: uglify-js1
/usr/bin/uglifyjs - from package: uglify-js
/usr/lib/node_modules/uglify-js@2/bin/uglifyjs - from package: uglify-js

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/uglifyjs - from package: node-uglify

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

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