Functions in javascript are lexically rather than dynamically scoped . this means that they run in the scope in which they are defined, not the scope from which they are executed 函數(shù)是常量作用范圍,而不是動(dòng)態(tài)作用范圍。這個(gè)意思就是說函數(shù)運(yùn)行在它定義好的域中,而不是在執(zhí)行執(zhí)行它的域。