![]() ![]() It returns the index within the calling String object of the first occurrence of the specified value. It calls a function for each element in the array. It returns the character at the specified index. Name some of the built-in methods and the values returned by them. To use a closure, simply define a function inside another function and expose it. In JavaScript, closures are created every time a function is created. It gives you access to an outer function’s scope from an inner function. What is Closure? Give an example.Ĭlosures are created whenever a variable that is defined outside the current scope is accessed from within some inner scope. Because of this, functions can take functions as arguments, and can be returned by other functions. It is a function that is to be executed after another function has finished executing, hence the name ‘ call back‘. What is Callback?Ī callback is a plain JavaScript function passed to some method as an argument or option. In a method, this refers to the owner object and in a function, this refers to the global object. This has different values depending on where it is used. The JavaScript this keyword refers to the object it belongs to. Q13. What is the purpose of ‘This’ operator in JavaScript? Function parameters are always local to that function. Local Variables − A local variable will be visible only within a function where it is defined.Global Variables − A global variable has global scope which means it is visible everywhere in your JavaScript code.JavaScript variable will have only two scopes. The scope of a variable is the region of your program in which it is defined. Q12. What are the scopes of a variable in JavaScript? JavaScript variable arguments represents the arguments that are passed to a function. Using type of operator, we can get the type of arguments passed to a function. Q11. What is argument objects in JavaScript & how to get the type of arguments passed to a function? In case you are facing any challenges with these JavaScript Interview Questions, please comment on your problems in the section below. It can also be passed as an argument to another function. Yes! An anonymous function can be assigned to a variable. Q10. Can you assign an anonymous function to a variable and pass it as an argument to another function? It can be defined using function keyword as : Q9. What is a name function in JavaScript & how to define it?Ī named function declares a name as soon as it is defined. You can define arrays using the array literal as follows. How can you create an Array in JavaScript? You can create an object using the object literal as follows − JavaScript supports Object concept very well. Q7. How can you create an object in JavaScript? Richer interfaces − You can use JavaScript to include such items as drag-and-drop components and sliders to give a Rich Interface to your site visitors.Increased interactivity − You can create interfaces that react when the user hovers over them with a mouse or activates them via the keyboard. ![]()
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