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JavaScript Questions & Answers – Expressions and Operators | JavaScript MCCs

(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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