sidtechtalks.in
01/12
02/12
Var – declares a variable and, optionally, initializes its value. Ex: var a =10; Variable declarations are processed before code execution. Const – functions are not permitted to modify the object to which they are called. A const function can be called on any type of object. Let – It indicates that the variable will only be used in the block in which it is defined.
03/12
1. A Document Object Model is a programming interface for HTML and XML documents. 2. When the browser tries to render an HTML document, it creates an object based on the HTML document called DOM. 3. Using this, we can manipulate or change various elements inside the HTML document.
04/12
Yes, we can assign an anonymous function to a variable. Moreover, it can be passed as an argument to another function, which is also called the Higher-Order Function.
05/12
this’ keyword refers to the object that the function is a property of. Depending on where it is used, it has different values function() { console.log(this); } This above function is a property of global object. And the global object is window object.
06/12
this’ keyword refers to the object that the function is a property of. Depending on where it is used, it has different values function() { console.log(this); } This above function is a property of global object. And the global object is window object.
07/12
A callback is a function that will be executed after another function gets executed. The function that is used as an argument to another function is called the Callback function.
08/12
1. Rest parameter should always be used as the last parameter of the function. It is used to take several arguments and turn them into an array. Whereas the Spread operator takes an array or an object and spreads it. 2. Rest is used in a function declaration, whereas the Spread operator is used in function calls.
09/12
It is a new way to extract elements from an object or an array. You don’t need to initialize the individual variables. It is easy to use, understand, and readable. For example: var {var1, var2, var3} = {'one', 'two', 'three'}
10/12
The event.preventDefault() method prevents the default behavior of an element. If used in a form element it prevents it from submitting. While the event.stopPropagation() method stops the propagation of an event. It stops the event from occurring in the bubbling or capturing phase. It does not prevent any default behaviors from occurring; for instance, clicks on links are still processed.
11/12
When the number of the function’s arguments are known to the programmer, as they have to be mentioned as arguments in the call statement. Similar to call() but the only difference is we don’t know the number of parameters in the function. So, we can pass the array like ([2, 3]) instead of (2, 3).
12/12
It is used to handle asynchronous operations in javascript. Before promises, callbacks were used to handle asynchronous operation. But due to limited functionality of callback, using multiple callbacks to handle async code can lead to unmanageable code. It has four states:- 1. Pending 2. Fulfilled 3. Rejected 4. Settled