uglifyjs1: 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/bin/uglifyjs1 - from package: uglify-js1

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

Error in other languages:
uglifyjs1: bevel nie gevind nie
uglifyjs1: comandă negăsită
uglifyjs1: comando não encontrado
uglifyjs1: commande introuvable
uglifyjs1: command not found
uglifyjs1: käsku ei ole
uglifyjs1: không tìm thấy lệnh
uglifyjs1: komanda nerasta
uglifyjs1: Kommando nicht gefunden.
uglifyjs1: kommandot finns inte
uglifyjs1: komut yok
uglifyjs1: nie znaleziono polecenia
uglifyjs1: níor aimsíodh an t-ordú
uglifyjs1: no se encontró la orden
uglifyjs1: no s'ha trobat l'ordre
uglifyjs1: opdracht niet gevonden
uglifyjs1: parancs nem található
uglifyjs1: perintah tidak ditemukan
uglifyjs1: príkaz nenájdený
uglifyjs1: příkaz nenalezen
uglifyjs1: команда не найдена
uglifyjs1: командата не е открита
uglifyjs1: 命令找不到
uglifyjs1: コマンドが見つかりません