Is `undefined` a type, a value, or both? [duplicate]












-2
















This question already has an answer here:




  • What is the type of undefined in javascript? [closed]

    2 answers





  1. Is undefined a type (data type), a value, or both?

  2. Can i use prototype to extendundefined





var i;

console.log(i) // => undefined

console.log(typeof i) // => undefined

    

var j = 2;

console.log(j) // => 2

console.log(typeof j) // => number








javascript types undefined prototype







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marked as duplicate by Sнаđошƒаӽ, deceze♦ javascript
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 Nov 14 '18 at 4:54


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.























    -2
















    This question already has an answer here:




    • What is the type of undefined in javascript? [closed]

      2 answers





    1. Is undefined a type (data type), a value, or both?

    2. Can i use prototype to extendundefined





    var i;
    
console.log(i) // => undefined
    
console.log(typeof i) // => undefined
    
    
    
var j = 2;
    
console.log(j) // => 2
    
console.log(typeof j) // => number








    javascript types undefined prototype







    share|improve this question













    marked as duplicate by Sнаđошƒаӽ, deceze♦ javascript
    Users with the  javascript badge can single-handedly close javascript questions as duplicates and reopen them as needed.

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     Nov 14 '18 at 4:54


    This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.





















      -2












      -2








      -2









      This question already has an answer here:




      • What is the type of undefined in javascript? [closed]

        2 answers





      1. Is undefined a type (data type), a value, or both?

      2. Can i use prototype to extendundefined





      var i;
      
console.log(i) // => undefined
      
console.log(typeof i) // => undefined
      
    
      
var j = 2;
      
console.log(j) // => 2
      
console.log(typeof j) // => number








      javascript types undefined prototype







      share|improve this question















      This question already has an answer here:




      • What is the type of undefined in javascript? [closed]

        2 answers





      1. Is undefined a type (data type), a value, or both?

      2. Can i use prototype to extendundefined





      var i;
      
console.log(i) // => undefined
      
console.log(typeof i) // => undefined
      
    
      
var j = 2;
      
console.log(j) // => 2
      
console.log(typeof j) // => number







      This question already has an answer here:




      • What is the type of undefined in javascript? [closed]

        2 answers







      var i;
      
console.log(i) // => undefined
      
console.log(typeof i) // => undefined
      
    
      
var j = 2;
      
console.log(j) // => 2
      
console.log(typeof j) // => number





      var i;
      
console.log(i) // => undefined
      
console.log(typeof i) // => undefined
      
    
      
var j = 2;
      
console.log(j) // => 2
      
console.log(typeof j) // => number





      javascript types undefined prototype




      javascript types undefined prototype






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked Nov 14 '18 at 4:49









      McKabueMcKabue

      6061716




      6061716




      marked as duplicate by Sнаđошƒаӽ, deceze♦ javascript
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       Nov 14 '18 at 4:54


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      marked as duplicate by Sнаđошƒаӽ, deceze♦ javascript
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       Nov 14 '18 at 4:54


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          1 Answer
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          1














          undefined



          1. Is undefined a type (data type), a value, or both?




          undefined is a property of the global object; i.e., it is a variable in global scope. The initial value of undefined is the primitive value undefined.




          2. Can i use prototype to extend undefined?




          In modern browsers (JavaScript 1.8.5 / Firefox 4+), undefined is a non-configurable, non-writable property per the ECMAScript 5 specification. Even when this is not the case, avoid overriding it.







          share|improve this answer






























            1 Answer
            1






            active

            oldest

            votes








            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            1














            undefined



            1. Is undefined a type (data type), a value, or both?




            undefined is a property of the global object; i.e., it is a variable in global scope. The initial value of undefined is the primitive value undefined.




            2. Can i use prototype to extend undefined?




            In modern browsers (JavaScript 1.8.5 / Firefox 4+), undefined is a non-configurable, non-writable property per the ECMAScript 5 specification. Even when this is not the case, avoid overriding it.







            share|improve this answer




























              1














              undefined



              1. Is undefined a type (data type), a value, or both?




              undefined is a property of the global object; i.e., it is a variable in global scope. The initial value of undefined is the primitive value undefined.




              2. Can i use prototype to extend undefined?




              In modern browsers (JavaScript 1.8.5 / Firefox 4+), undefined is a non-configurable, non-writable property per the ECMAScript 5 specification. Even when this is not the case, avoid overriding it.







              share|improve this answer


























                1












                1








                1







                undefined



                1. Is undefined a type (data type), a value, or both?




                undefined is a property of the global object; i.e., it is a variable in global scope. The initial value of undefined is the primitive value undefined.




                2. Can i use prototype to extend undefined?




                In modern browsers (JavaScript 1.8.5 / Firefox 4+), undefined is a non-configurable, non-writable property per the ECMAScript 5 specification. Even when this is not the case, avoid overriding it.







                share|improve this answer













                undefined



                1. Is undefined a type (data type), a value, or both?




                undefined is a property of the global object; i.e., it is a variable in global scope. The initial value of undefined is the primitive value undefined.




                2. Can i use prototype to extend undefined?




                In modern browsers (JavaScript 1.8.5 / Firefox 4+), undefined is a non-configurable, non-writable property per the ECMAScript 5 specification. Even when this is not the case, avoid overriding it.








                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered Nov 14 '18 at 4:54









                MamunMamun

                26.5k71630




                26.5k71630















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