[JavaScript] PEGjs

（1）安装pegjs

bower install pegjs

（2）index.html

（3）页面中使用

var parser=window.PEG.buildParser('\
    start\n\
      = additive\n\
    \n\
    additive\n\
      = left:multiplicative "+" right:additive { return left + right; }\n\
      / multiplicative\n\
    \n\
    multiplicative\n\
      = left:primary "*" right:multiplicative { return left * right; }\n\
      / primary\n\
    \n\
    primary\n\
      = integer\n\
      / "(" additive:additive ")" { return additive; }\n\
    \n\
    integer "integer"\n\
      = digits:[0-9]+ { return parseInt(digits.join(""), 10); }\n\
    ');

var result=parser.parse('1+2*3');
console.log(result);