Is `undefined` a type, a value, or both? [duplicate]
This question already has an answer here:
What is the type of undefined in javascript? [closed]
2 answers
- Is
undefineda type (data type), a value, or both? - Can i use prototype to extend
undefined
var i;
console.log(i) // => undefined
console.log(typeof i) // => undefined
var j = 2;
console.log(j) // => 2
console.log(typeof j) // => numberjavascript types undefined prototype
asked Nov 14 '18 at 4:49
McKabueMcKabue
6061716
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.
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This question already has an answer here:
What is the type of undefined in javascript? [closed]
2 answers
- Is
undefineda type (data type), a value, or both? - Can i use prototype to extend
undefined
var i;
console.log(i) // => undefined
console.log(typeof i) // => undefined
var j = 2;
console.log(j) // => 2
console.log(typeof j) // => numberjavascript types undefined prototype
asked Nov 14 '18 at 4:49
McKabueMcKabue
6061716
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.
add a comment |
This question already has an answer here:
What is the type of undefined in javascript? [closed]
2 answers
- Is
undefineda type (data type), a value, or both? - Can i use prototype to extend
undefined
var i;
console.log(i) // => undefined
console.log(typeof i) // => undefined
var j = 2;
console.log(j) // => 2
console.log(typeof j) // => numberjavascript types undefined prototype
asked Nov 14 '18 at 4:49
McKabueMcKabue
6061716
This question already has an answer here:
What is the type of undefined in javascript? [closed]
2 answers
- Is
undefineda type (data type), a value, or both? - Can i use prototype to extend
undefined
var i;
console.log(i) // => undefined
console.log(typeof i) // => undefined
var j = 2;
console.log(j) // => 2
console.log(typeof j) // => numberThis 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) // => numbervar i;
console.log(i) // => undefined
console.log(typeof i) // => undefined
var j = 2;
console.log(j) // => 2
console.log(typeof j) // => numberjavascript types undefined prototype
javascript types undefined prototype
asked Nov 14 '18 at 4:49
McKabueMcKabue
6061716
asked Nov 14 '18 at 4:49
McKabueMcKabue
6061716
asked Nov 14 '18 at 4:49
McKabueMcKabue
6061716
asked Nov 14 '18 at 4:49
McKabueMcKabue
6061716
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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Nov 14 '18 at 4:54
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1 Answer
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undefined
1. Is undefined a type (data type), a value, or both?
undefinedis a property of the global object; i.e., it is a variable in global scope. The initial value ofundefinedis the primitive valueundefined.
2. Can i use prototype to extend undefined?
In modern browsers (JavaScript 1.8.5 / Firefox 4+),
undefinedis a non-configurable, non-writable property per the ECMAScript 5 specification. Even when this is not the case, avoid overriding it.
answered Nov 14 '18 at 4:54
MamunMamun
26.5k71630
add a comment |
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
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active
oldest
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active
oldest
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undefined
1. Is undefined a type (data type), a value, or both?
undefinedis a property of the global object; i.e., it is a variable in global scope. The initial value ofundefinedis the primitive valueundefined.
2. Can i use prototype to extend undefined?
In modern browsers (JavaScript 1.8.5 / Firefox 4+),
undefinedis a non-configurable, non-writable property per the ECMAScript 5 specification. Even when this is not the case, avoid overriding it.
answered Nov 14 '18 at 4:54
MamunMamun
26.5k71630
add a comment |
undefined
1. Is undefined a type (data type), a value, or both?
undefinedis a property of the global object; i.e., it is a variable in global scope. The initial value ofundefinedis the primitive valueundefined.
2. Can i use prototype to extend undefined?
In modern browsers (JavaScript 1.8.5 / Firefox 4+),
undefinedis a non-configurable, non-writable property per the ECMAScript 5 specification. Even when this is not the case, avoid overriding it.
answered Nov 14 '18 at 4:54
MamunMamun
26.5k71630
add a comment |
undefined
1. Is undefined a type (data type), a value, or both?
undefinedis a property of the global object; i.e., it is a variable in global scope. The initial value ofundefinedis the primitive valueundefined.
2. Can i use prototype to extend undefined?
In modern browsers (JavaScript 1.8.5 / Firefox 4+),
undefinedis a non-configurable, non-writable property per the ECMAScript 5 specification. Even when this is not the case, avoid overriding it.
answered Nov 14 '18 at 4:54
MamunMamun
26.5k71630
undefined
1. Is undefined a type (data type), a value, or both?
undefinedis a property of the global object; i.e., it is a variable in global scope. The initial value ofundefinedis the primitive valueundefined.
2. Can i use prototype to extend undefined?
In modern browsers (JavaScript 1.8.5 / Firefox 4+),
undefinedis a non-configurable, non-writable property per the ECMAScript 5 specification. Even when this is not the case, avoid overriding it.
answered Nov 14 '18 at 4:54
MamunMamun
26.5k71630
answered Nov 14 '18 at 4:54
MamunMamun
26.5k71630
answered Nov 14 '18 at 4:54
MamunMamun
26.5k71630
answered Nov 14 '18 at 4:54
MamunMamun
26.5k71630
26.5k71630
add a comment |
add a comment |
