JavaScript Functions- Summary:
In this video we have covered JS variables. Think of variables as containers for storing data. There are three types: "var," "let," and "const." "Var" used to be the old way to declare variables but can lead to some tricky issues (more about it in our future videos), so it's not commonly used anymore. "Let" is for variables that can change their value, and "const" is for constants, which means their value can't be changed once set. Choosing the right one depends on whether you want your variable to be flexible or stay constant. So, in a nutshell, they help us manage and manipulate data in our JavaScript code. Let's review each in more details:
JS Variables: 'var'
The 'var' variable used to be the way to declare variables in JavaScript. However, since, in simple terms, it really didn't care much about where you declared it (We'll talk more about function scope in our future videos), it did cause a lot of confusion and bugs. That's why nowadays, we tend to use 'let' and 'const' more often. But 'var' still exists in some older code, so it's good to know about it, even if we try to avoid using it in modern JavaScript. To declare a variable using 'var,' we simply write: var variableName ;
Please note that we have only declared a variable with the name 'VariableName' and have not initialized it yet. To initialize a variable, we need to assign a value to it. Using the example above, it would look like this: var variableName = value;
JS Variables: "Let"
When we use 'let,' we are declaring a variable that's block-scoped. It's a fancy term, which means it's limited to the block, function, or statement where it's defined. It's a significant improvement over 'var' because it enforces a cleaner, more predictable scope for your variables.
This helps prevent unintended side effects and makes our code easier to reason about. Variable 'let' is perfect for situations where we want to restrict the variable's access to a specific part of your code, ensuring that changes made within that scope won't affect the outside world, enhancing code maintainability and reliability. If needed, we can reassign the value of a 'let' variable. 'let' is declared and initialized the same way as 'var'.
JS Variables: "const'
Variable "const" in JavaScript represents a constant variable. Once we assign a value to a "const" variable, we can't change it. It's like naming a value and saying, "This won't budge." This is incredibly useful for situations where we want to ensure that a variable remains constant throughout your code, preventing accidental changes.
However, it's important to note that "const" doesn't mean the value itself can't change if it's an object or an array. It means we can't reassign the variable to a different value. So, if we have a "const" object, we can still modify its properties, but we can't point the "const" variable to a completely different object. We'll talk more about it in our future videos.
Now is your turn! Remember: "Practice makes perfect"!
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