You now have other options, and in this unit we go over why you want to use them. To begin, let's look a little closer at how variables are defined. Variables declared with the var keyword are said to be in the function scope. This means that a variable would ex...
let is the same as const in that both are blocked-scope. It means that the variable is only available within its scope. Arrow functions: ()=>{} The arrow function is really awesome, and makes your code more readable, more structured, and look like modern code. Instead of using this: ...
Now, in ES6 you can specify default values to the function parameters. This means that if no arguments are provided to function when it is called these default parameters values will be used. This is one of the most awaited features in JavaScript. Here's an example:...
In the above example, we included the default parameter valuenumB = 5in the function declaration. This means, even if you don't pass the parameter fornumB, it will take5by default. To learn more about default parameters, visitJavaScript Default Parameters. JavaScript Arrow Function ES6 introduce...
WeakMap class in Javascript ES6 introduced new collection data structures and classes.WeakMapis one of these collection classes, similar to the WeakMapis a map class that stores keys and values, with keys storing weak references. This means that if the key’s reference is unreferenced, the val...
This means that declaring let variables in a for loop, inside an if or in a in block is not going to let that variable escape the block, while var s are hoisted up to the function definition. const is just like let , but immutable. In JavaScript moving forward, youll see little to...
// No requestAnim. means no cancelAnim. Built that too. cancelAnimationFrame = function(id) { clearTimeout(id); } } // Now you can use requestAnimationFrame // No matter which browser you're running var animationID = requestAnimationFrame(myBeautifulFunction); ...
在此示例中,入口点从模块A导入,模块从模块C导入,模块从模块B导入This means moduleBwill be evaluated before moduleC, but due to the fact that the exportedinitCfunction from moduleCis hoisted , moduleBwill be given a reference to thisinitCfunction, and therefore moduleBcall callinitCbefore module...
JavaScript is case-sensitive. This means that JavaScript differentiates between the uppercase and the lowercase characters. Semicolons are Optional Each line of instruction is called a statement. Semicolons are optional in JavaScript. Example console.log("hello world") console.log("We are learning...
Fortunately in ES6, arrow functions use ‘lexical scoping’ (which basically means it uses this from the surrounding code). We can keep the scope of our original scope by passing it a reference to the execution context that we called it from.Conclusion...