# The Case-Sensitivity of JavaScript
The statement "JavaScript is not a case-sensitive language" is false. In fact, JavaScript is a case-sensitive language. This means that it differentiates between upper-case and lower-case letters when interpreting code.
## Case-Sensitivity in JavaScript
In JavaScript, variables, function names, and other identifiers must be consistently cased. For example, the variables `myVariable`, `MyVariable` and `MYVARIABLE` would be treated as three separate entities in JavaScript.
```javascript
let myVariable = 5;
let MyVariable = 10;
let MYVARIABLE = 15;
console.log(myVariable); // Outputs: 5
console.log(MyVariable); // Outputs: 10
console.log(MYVARIABLE); // Outputs: 15
```
In the above example, each variable, despite having the same spelling, is treated as a separate variable due to the variation in case.
Another impact of JavaScript's case sensitivity comes into play with in-built methods or properties. A good example would be the JavaScript `toLowerCase()` method. If you incorrectly write this method as `toLowercase()`, `tolowerCase()`, or any other case variation, it will result in a JavaScript error, because these are not recognized by the JavaScript engine.
```javascript
let text = "Hello World";
console.log(text.tolowerCase()); // Incorrect usage, results in a TypeError
console.log(text.toLowerCase()); // Correct usage, outputs: "hello world"
```
## Best Practices and Additional Insights
When scripting in JavaScript, it is considered best practice to stick to a consistent use of case. One common style is camelCase, where the first letter of each word except the first is capitalized (for example, `myVariableName`). This improves readability, making your code easier to understand for other developers.
Also understand that capitalization in JavaScript can also convey certain conventions or meanings. For instance, it's a commonly accepted convention to only use PascalCase (same as camelCase, but the first letter is capitalized, like `MyVariableName`) for constructor functions and ES6 classes.
In conclusion, capitalization plays a significant, functional role in a JavaScript application. Its case-sensitive nature shouldn't be overlooked, as doing so may lead to unexpected results and errors in your code. Remembering that JavaScript is indeed a case-sensitive language is hence critical for successful coding.