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Copy file name to clipboardExpand all lines: Notes/3-Hoisting.md
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@@ -16,15 +16,15 @@ console.log(x);
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Output:
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> Namaste JavaScript
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> Namaste JavaScript
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> 7
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> 7
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```
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// code example 2
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getName(); // in most languages, both lines which are above their declaration will give error. Not in JS though.
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console.log(x);
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getName(); // in most languages, both lines which are above their declaration will give error. Not in JS though.
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console.log(x);
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var x = 7;
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@@ -34,10 +34,11 @@ function getName(){
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```
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Output:
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> Namaste JavaScript
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Output:
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> Namaste JavaScript
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> undefined
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> undefined
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```
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// code example 3
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Output:
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> Namaste JavaScript
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> Namaste JavaScript
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> Error: x is not defined // note that not defined here and "undefined" in sample 2 are totally different.
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> Error: x is not defined // note that not defined here and "undefined" in
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> sample 2 are totally different.
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- Not defined: We have not initialised the value for variable anywhere in the entire code and in memory space.
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- Undefined:
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- Not defined: We have not initialised the value for variable anywhere in the
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entire code and in memory space.
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- Undefined: It is a placeholder that is assigned to a variable by the
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Javascript Engine until the variable is assigned with some other value.
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__Hoisting__ is a concept which enables us to extract values of variables and functions even before initialising/assigning value without getting *error*
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**Hoisting** is a concept which enables us to extract values of variables and
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functions even before initialising/assigning value without getting _error_
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```
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@@ -78,9 +83,10 @@ console.log(getName)
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Output:
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> f getName(){
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console.log("Namaste JavaScript);
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}
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}
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```
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@@ -99,13 +105,16 @@ function getName(){
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```
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Output:
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> Namaste JavaScript
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> undefined
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> Namaste JavaScript
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> undefined
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> f getName(){
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> f getName(){
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console.log("Namaste JavaScript);
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}
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}
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```
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// code example 6
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console.log("Namaste JavaScript");
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}
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var getName = () => { // use fat arrow function
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var getName = () => { // use fat arrow function
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console.log("Namaste JavaScript");
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}
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```
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Output:
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> undefined //it is because they behave as variable and not function.
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> undefined //it is because they behave as variable and not function.
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---
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__REASON OF WEIRDNESS__
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* The answer lies in the Global Exection Context. In the memory phase, the variables will be initialized as *undefined* and functions will get the whole function code in their memory.
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* This is the reason why we are getting these outputs.
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**REASON OF WEIRDNESS**
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- The answer lies in the Global Exection Context. In the memory phase, the
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variables will be initialized as _undefined_ and functions will get the whole
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function code in their memory.
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- This is the reason why we are getting these outputs.
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