JS 判断 undefined与null

    xiaoxiao2022-06-28  34

    1.判断undefined 

    var      data=2;

    if( typeof data =='undefined'){

    alert('is undefined');

    }else{

    alert('is not undefined');

    }

    2.判断null

    var exp=null;

    if(!exp && typeof exp != "undefined" && exp != 0){

    alert('is null');

    }else{

    alert('not null');

    }

    转载请注明原文地址: https://ju.6miu.com/read-1124648.html

    最新回复(0)