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JavaScript Questions & Answers – Expressions and Operators | JavaScript MCCs

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Free download in PDF JavaScript Multiple Choice Questions and Answers for competitive exams. These short objective type questions with answers are very important for Board exams as well as competitive exams like UPSC, NDA, SSC etc. These short solved questions or quizzes are provided by Gkseries./p>

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(1) What will be the output of the following JavaScript code? 
var string1 = ”123”;
var intvalue = 123;
alert( string1 + intvalue );
[A] 123246
[B] 246
[C] 123123
[D] Exception
Answer: 123123
(2) A function definition expression can be called as __________
[A] Function prototype
[B] Function literal
[C] Function calling
[D] Function declaration
Answer: Function literal

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(3) The property of a primary expression is ____________
[A] stand-alone expressions
[B] basic expressions containing all necessary functions
[C] contains variable references alone
[B] contains only keywords
Answer: stand-alone expressions
(4)

Consider the following JavaScript statements.

var text = "testing: 1, 2, 3"; // Sample text

var pattern = /\d+/g // Matches all instances of one or more digits

In order to check if the pattern matches with the string “text”, the statement is ____________

[A] text==pattern
[B] text.equals(pattern)
[C] text.test(pattern)
[D] pattern.test(text)
Answer: pattern.test(text)
(5) The expression of calling (or executing) a function or method in JavaScript is called ________
[A] Primary expression
[B] Functional expression
[C] Invocation expression
[B] Property Access Expression
Answer: Invocation expression
(6) What kind of expression is “new Point(2,3)”?
[A] Primary Expression
[B] Object Creation Expression
[C] Invocation Expression
[D] Constructor Calling Expression
Answer: Object Creation Expression
(7) Which of the operator is used to test if a particular property exists or not?
[A] in
[B] exist
[C] within
[D] exists
Answer: in
(8) Among the following, which one is a ternary operator?
[A] +
[B] :
[C] –
[D] ?:
Answer: ?:
(9) “An expression that can legally appear on the left side of an assignment expression.” is a well known explanation for variables, properties of objects, and elements of arrays. They are called ___________
[A] Properties
[B] Prototypes
[C] Lvalue
[D] Definition
Answer: Lvalue
(10) What will be the equivalent output of the following JavaScript code snippet? 
x = ~-y;
w = x = y = z;
q = a?b:c?d:e?f:g;
[A] 
x = ~(-y); w = (x = (y = z));
q = a?b:(c?d:(e?f:g));
[B] 
x = a?b:(c?d:(e?f:g));
q = ~(-y); w = (x = (y = z));
[C] 
x = (x = (y = z));w = ~(-y);
q = a?b:(c?d:(e?f:g));
[D] 
x = ~(-y); w = (x = (y = z)); 
q = (c?d:(e?f:g));
Answer: 
x = ~(-y); w = (x = (y = z));
q = a?b:(c?d:(e?f:g));
(11) What will be the output of the following JavaScript code? 
function output(option)
{
	return (option ?  “yes” :  “no”);
}
	bool ans=true;
console.log(output(ans));
[A] Yes
[B] No
[C] Runtime error
[B] Compilation error
Answer: Yes
(12) What will be the output of the following JavaScript code? 
var  obj=
{
	length:20,
	height:35,
}
if (‘breadth' in obj === false)
{
  	obj.breadth = 12;
} 
console.log(obj.breadth);
[A] 20
[B] 12
[C] undefined
[D] error
Answer: 12
(13) What will be the output of the following JavaScript code? 
function height()
{
   var  height = 123.56;
    var type = (height>=190) ? "tall" : "short";

   return type;
}
[A] 123.56
[B] 190
[C] tall
[D] short
Answer: short
(14) What will be the output of the following JavaScript code? 
string  a = ”hi”;
string  b =”there”;
alert(a+b);
[A] hi
[B] there
[C] hithere
[D] undefined
Answer: hithere
(15) What will be the output of the following JavaScript code? 
function output(object)
{
	var place=object ? object.place : “Italy”;
	return “clean:”+ place;

}
console.log(output({place:India}));
[A] clean:India
[B] clean:Italy
[C] error
[D] undefined
Answer: clean:India

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