[digits][.digits][(E|e)[(+|-)]digits]
[digits][+digits][(E|e)[(+|-)]digits]
[digits][(E|e)[(+|-)]digits]
[.digits][digits][(E|e)[(+|-)]digits]
A. [digits][.digits][(E|e)[(+|-)]digits]
var a = [1,2,3,4,5];
a.slice(0,3);
Returns [1,2,3]
Returns [4,5]
Returns [1,2,3,4]
Returns [1,2,3,4,5]
RMI
Triggering Event
Preprocessor
Function/Method
int a==2;
int b=4;
int ans=a+b;
print(ans);
2
6
0
error
var text = testing: 1, 2, 3; // Sample text
var pattern = /d+/g // Matches all instances of one or more digits
text==pattern
text.equals(pattern)
text.test(pattern)
pattern.test(text)
const object1 = {};
a = Symbol('a');
b = Symbol.for('b');
object1[a] = 'harry';
object1[b] = 'derry';
const objectSymbols = Object.getOwnPropertySymbols(object1);
console.log(objectSymbols.length);
0
2
1
Error
It is mandatory
Not necessary
Few functions return values by default
some functions do not return any value
for(var p in o)
console.log(o[p]);
for (var i = 0;i < a.length;i++)
console.log(a[i]);
for (int i = 0;i < a.length;i++)
console.log(a[i]);
for (var i = 0;i <= a.length;i++)
console.log(a[i]);
for (var i = 1;i < a.length;i++)
console.log(a[i]);
var a = 10;
do {
a += 1;
console.log(a);
} while (a < 5);
11121314
1112
12345
11
function output(object)
{
var place=object ? object.place : Italy;
return clean:+ place;
}
console.log(output({place:India}));
clean:India
clean:Italy
error
undefined
for(var num=10;num>=1;num--)
{
document.writeln(num);
}
var num=10;
while(num>=1)
{
document.writeln(num);
num++;
}
Code 1
Code 2
Both Code 1 and Code 2
Cannot Compare
var grade='B';
var result;
switch(grade)
{
case 'A':
{
result+=10;
break;
}
case 'B':
{
result+= 9;
break;
}
case 'C':
{
result+= 8;
break;
}
default:
result+= 0;
}
document.write(result);
10
9
8
0
125
25
5
Error
function f(o)
{
if (o === undefined) debugger;
}
It does nothing but a simple breakpoint
It debugs the error in that statement and restarts the statements execution
It is used as a keyword that debugs the entire program at once
It is used to find error in the statement
const obj1 =
{
property1: 21
}
const descriptor1 = Object.getOwnPropertyDescriptor(obj1, 'property1');
console.log(descriptor1.configurable);
console.log(descriptor1.enumerable);
true 21
true false
true true
false false
Reverses and stores in the same array
Reverses and concatenates the elements of the array
Reverses
Stores the elements of an array in normal order
conditional block
block that contains a single statement
both conditional block and a single statement
block that combines multiple statements into a single compound statement
debugger
with
if
use strict
int a=4;
int b=1;
int c=0;
If(a==b)
document.write(a);
else if(a==c)
document.write(a);
else
document.write(c);
4
1
Error
0
The property will be stored in a cache
The loop will not run
That property will not be enumerated
The property will be enumerated
+
:
^
?:
Keywords
Declaration statements
Data types
Prototypes
var arr = [7, 5, 9, 1];
var min = Math.min.apply(null, arr);
document.writeln(min);
7
5
1
9
function printArray(a)
{
var len = a.length, i = 0;
if (len == 0)
console.log(Empty Array);
else
{
do
{
console.log(a[i]);
} while (++i < len);
}
}
Prints the numbers in the array in order
Prints the numbers in the array in the reverse order
Prints 0 to the length of the array
Prints Empty Array
var a=3.7;
var b=2;
a=ciel(a)
document.writeIn(a*b);
6
7.4
7.5
8
Properties
Prototypes
Lvalue
Definition
var arr=[1,2,3];
var rev=arr.reverse();
document.writeln(rev);
1, 2, 3
3, 2, 1
3
1
Floating numbers
Representation of functions that returns a value
is not present in JavaScript
Form feed
function tail(o)
{
for (; o.next; o = o.next) ;
return o;
}
No, this will throw an exception as only numerics can be used in a for loop
No, this will not iterate
Yes, this will work
No, this will result in a runtime error with the message Cannot use Linked List
isPrototypeOf() method
equals() method
=== operator
==opertor
var book = {
main title: JavaScript,
'sub-title': The Definitive Guide,
for: all audiences,
author: {
firstname: David,
surname: Flanagan
}
};
properties
property values
property names
objects