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java-script:hoisting [2023/08/08 23:50] – created odeftajava-script:hoisting [2023/08/09 00:32] (current) – odefta
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 ===== Variable hoisting ===== ===== Variable hoisting =====
 +
 +==== Using var keyword ====
  
 ;;;The variable declaration using var is hoisted, but the initialization is not.;; So, if you reference a variable before it's initialized, it will return undefined. \\  ;;;The variable declaration using var is hoisted, but the initialization is not.;; So, if you reference a variable before it's initialized, it will return undefined. \\ 
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 console.log(a); // 5 console.log(a); // 5
 </code> </code>
 +
 +<note important>
 +Hoisting does not apply to variables declared with **let** and **const**; trying to access them before their declaration will result in a **ReferenceError**.
 +</note>
 +
 +==== Without any keyword ====
 +
 +;;;Variables that are declared without any keyword;;; (such as var, let, or const) ;;;are not hoisted;;;. Rather, **they become global variables** (if not already within a global scope), and their declaration and initialization happen at the line where they are assigned. \\ 
 +
 +Example:
 +<code javascript>
 +console.log(myVar); // ReferenceError: myVar is not defined
 +myVar = "abc";
 +console.log(myVar); // "abc"
 +</code>
 +
 +In this case, **myVar** is not declared or initialized before the first console.log, so attempting to access it results in a **ReferenceError**.\\ \\ 
 +
 +If you were to declare the variable without initializing it within a function, **it would be hoisted as a property of the global object** (such as window in a browser environment):
 +<code>
 +function myFunction() {
 +  myVar = "abc";
 +}
 +myFunction();
 +console.log(window.myVar); // "abc" in a browser environment
 +</code>
 +This behavior can lead to unexpected results and make the code harder to understand and maintain. 
  
 ===== Functions ===== ===== Functions =====
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 <note important> <note important>
-Hoisting does not apply to variables declared with **let** and **const**; trying to access them before their declaration will result in a **ReferenceError**. +;;;Function expressions (including arrow functions) are NOT hoisted like function declarations;;;, so their behavior is more like that of variables declared with **var**. \\ 
-</note> +
- +
-<note important> +
-Function expressions (including arrow functions) are not hoisted like function declarations, so their behavior is more like that of variables declared with **var**. \\ +
 Only the variable declaration is hoisted, not the initialization with the function value. \\  Only the variable declaration is hoisted, not the initialization with the function value. \\ 
 Example: Example:
java-script/hoisting.1691527808.txt.gz · Last modified: 2023/08/08 23:50 by odefta