摘要： in 运算符判断对象是否拥有某一属性只要对象拥有该属性，就会返回true，否则falsevar point = { x:1, y:1 };alert( 'x' in point ); //truevar arr = ['one', 'two'];alert( 'kang' in arr ); //falsealert( '1' in arr ); //truealert( 'push' in arr ); //truevar fn = function(){};fn.prototype.site = 阅读全文