CODEWITHSUNDEEP
javascript
Rajasekhar
Rajasekhar

Reputation: 2455

Unable to perform validation using null || undefined || "" values

I have one validation that I need to perform. When a string is null or undefined or "" I need to show a message like "unable to perform further steps". If I do have values I need to proceed with further validations. I tried below code, but it doesn't work.

function test(){

  var value = undefined; // api returns undefined

  if(value != "" || value != undefined || value != null){
     alert("ID::: " + value);
     //next validations      
  }else{
    alert("Id is blank, we are unable to process the request!!!");   
    return false; 
  }

}
<button type="button"onclick="test()">Click</button>

Upvotes: 1

Views: 414

Answers (3)

Neha Soni
Neha Soni

Reputation: 4694

Try this-

function test(){

  var value1 = undefined; // If api returns undefined
  var value2 = null; // If api returns null
  var value3 = ""; // If api returns empty string
  var value4 = 45; // If api returns any value
  
  examineValue(value1);
  examineValue(value2);
  examineValue(value3);
  examineValue(value4);
      
}

function examineValue(value) {
  if(value === "" || value === undefined || value === null){
    alert("Id is blank, we are unable to process the request!!!");   
    return false;
  }
  alert("ID::: " + value);
  //next validations  
}
<button type="button"onclick="test()">Click</button>

Upvotes: 1

Jurshsmith
Jurshsmith

Reputation: 182

Using !someVariable converts to a boolean and handles those checks automatically

function test(){

  var value = undefined; // api returns undefined

  if(!value){
    alert("Id is blank, we are unable to process the request!!!");   
    return false; 
 }

 alert("ID::: " + value);
 //next validations  

}
<button type="button"onclick="test()">Click</button>

Upvotes: 1

张立伟
张立伟

Reputation: 11

function test(){

  var value = undefined; // api returns undefined

  if(value != "" && value != undefined && value != null){
     alert("ID::: " + value);
     //next validations      
  }else{
    alert("Id is blank, we are unable to process the request!!!");   
    return false; 
  }

}
<button type="button"onclick="test()">Click</button>

Upvotes: 1

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