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 Parantheses
b) Return type and Identifier
c) Return type, Function keyword, Identifier and Parantheses
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 parantheses 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) All of the mentioned
d) None of the mentioned
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) All of the mentioned
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 statement causes the function to stop executing and to return the value of its expression (if any) to the caller.
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) None of the mentioned
View Answer
Explanation: If the return statement does not have an associated expression, it returns the undefined value.
6. A function with no return value is called
a) Procedures
b) Method
c) Static function
d) Dynamic function
View Answer
Explanation: 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 acceess 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 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).
Sanfoundry Global Education & Learning Series – Javascript Programming.
