This set of Javascript Multiple Choice Questions & Answers (MCQs) focuses on “Defining and Invoking Functions”.
1. The function definitions in JavaScript begins with
a) Identifier and Parentheses
b) Return type and Identifier
c) Return type, Function keyword, Identifier and Parentheses
d) Identifier and Return type
View Answer
Explanation: The function definitions begin with the keyword function followed by an identifier that names the function and a pair of parentheses around a comma-separated list of zero or more identifiers.
2. Consider the following code snippet
function printprops(o) { for(var p in o) console.log(p + ": " + o[p] + "\n"); }
What will the above code snippet result ?
a) Prints the contents of each property of o
b) Returns undefined
c) prints only one property
d) prints the address of elements
View Answer
Explanation: The above code snippet returns undefined.
3. When does the function name become optional in JavaScript?
a) When the function is defined as a looping statement
b) When the function is defined as expressions
c) When the function is predefined
d) when the function is called
View Answer
Explanation: The function name is optional for functions defined as expressions. A function declaration statement actually declares a variable and assigns a function object to it.
4. What is the purpose of a return statement in a function?
a) Returns the value and continues executing rest of the statements, if any
b) Returns the value and stops the program
c) Returns the value and stops executing the function
d) Stops executing the function and returns the value
View Answer
Explanation: The return stops the execution of the function when it is encountered within the function.It returns the value to the statement where the function is called.
5. What will happen if a return statement does not have an associated expression?
a) It returns the value 0
b) It will throw an exception
c) It returns the undefined value
d) It will throw an error
View Answer
Explanation: A function without a return statement will return a default value. ifthe return statement does not have an associated expression then it returns an undefined value.
6. A function with no return value is called
a) Procedures
b) Method
c) Static function
d) Dynamic function
View Answer
Explanation: Void functions does not return a value. Functions with no return value are sometimes called procedures.
7. Consider the following code snippet
function hypotenuse(a, b) { function square(x) { return x*x; } return Math.sqrt(square(a) + square(b)); }
What does the above code result?
a) Sum of square of a and b
b) Square of sum of a and b
c) Sum of a and b square
d) None of the mentioned
View Answer
Explanation: The above code snippet contains nested function in which the function hypotenuse(a,b) has another function inside its scope, function square(x). The interesting thing about nested functions is their variable scoping rules. They can access the parameters and variables of the function (or functions) they are nested within.
8. Which of the following is the correct code for invoking a function without this keyword at all, and also too determine whether the strict mode is in effect?
a) var strict = (function { return this; }); b) mode strict = (function() { return !this; }()); c) var strict = (function() { return !this; }()); d) mode strict = (function { });
Explanation: The above code defines and invokes a function to determine if we’re in strict mode.
9. Which is an equivalent code to invoke a function m of class o that expects two arguments x and y?
a) o(x,y); b) o.m(x) && o.m(y); c) m(x,y); d) o.m(x,y);
Explanation: The two argument in a function are separated by a comma (,). The code above is an invocation expression: it includes a function expression o.m and two argument expressions, x and y.
10. Consider the following code snippet
o.m(x,y);
Which is an equivalent code for the above code snippet?
a) o.m(x) && o.m(y); b) o["m"](x,y); c) o(m)["x","y"]; d) o.m(x && y);
Explanation: Another way to write o.m(x,y) is o[“m”](x,y).o[“m”] will access the property of the object and parenthesis will access the function present inside it.
Sanfoundry Global Education & Learning Series – Javascript Programming.