Question

16

how to check if variable is blank or undefined in node js

rated 0 times [ 22] [ 6] / answers: 1 / hits: 34175 / 9 Years ago, tue, january 19, 2016, 12:00:00

I want to check my data is blank or undefined but my if block execute even my data is not blank ...

Code is :

router.post('/addNewGrade',function(req , res){ 

    var errorMsg = [];  

    console.log(req.body.gradeName)

    if(req.body.gradeName == '' || req.body.gradeName === undefined){

        errorMsg.push(please enter grade name);

    }

    if(req.body.gradeDescription == '' || req.body.gradeDescription === undefined){

        errorMsg.push(please enter description about your grade);

    }

    if(errorMsg !=''){

        res.send({errorMessage :errorMsg}); 

        return;

    }



});

what is the best way to check variable is undefined or not

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micheleb

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4 Years ago

answered 9 Years ago margaritakristinak · Accepted Answer

Because an undefined variable is falsey, you can simple do

if (body.req.gradeName) {

  // do normal stuff

} else {

  // do error stuff

}

Or if you don't need to do anything if it is defined, then you can do

if (!(body.req.gradeName)) {

 // do error stuff 

}