One Simple JavaScript Like Lauguage Interpreter

• current support keyword
  • let
  • if
  • else
  • while
  • function
  • return
• current support operator
  • + plus (number and number, string and string)
  • - minus (number and number)
  • * multiply（number and number）
  • / divid (number and number)
  • > greater (number and number)
  • < less (number and number)
  • >= greater or equal (number and number)
  • <= less or equal (number and number)
  • == equal (number and number)
  • != not equal (number and number)