为什么我的运行后没反映

Question

为什么我的运行后没反映按f12显示index:94 Uncaught TypeError: $ is not a function     at menuFire (index:94)     at HTMLAnchorElement.onclick (index:53)

index.html92-96行代码: 

function menuFire(obj){var src = $(obj).attr('src');$('iframe').attr('src',src);}