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The else clause is optional

Note that when writing JavaScript code, the else clause shown in Figure 5 is optional. In other words, you might choose to direct the script to take some specific action if the condition is true, but simply transfer control to thenext sequential statement in the script if the condition is false.

A selection script example

Listing 3 shows a sample script containing two selection statements (commonly called if-else statements) in sequence.

Listing 3 . A selection script example.
<!-- File JavaScript03.html --><html><body><script language="JavaScript1.3">if(3>2){ document.write("3 is greater than 2.","</br>") }else{document.write("3 is not greater than 2.") }//end ifif(3<2){ document.write("3 is less than 2.","</br>") }else{document.write("3 is not less than 2.") }//end if</script></body></html>

If 3 is greater than 2...

The conditional clause in the first if statement in Listing 3 uses the "greater-than" relational operator ">" to determine if the literal value 3 is greater than the literal value 2, producing the first line of output shown in Figure 6 .

Figure 6 . Output from script in Listing 3 .
3 is greater than 2. 3 is not less than 2.

The test returns true

Since 3 is always greater than 2, the statement in the line immediately following the first test in Listing 3 is executed and the code in the line following the word else is skipped producing the first line of output text shown in Figure 6 .

If 3 is less than 2...

The conditional clause in the second if statement in Listing 3 uses the "less-than" relational operator (see Figure 7 ) to determine if the literal value 3 is less than the literal value 2.

The test returns false

Since 3 isn't less than 2, the statement in the line immediately following the second test in Listing 3 is skipped and the statement in the line immediately following the second word else is executed producing the second line of output text shown in Figure 6 .

Relational and logical operators

I doubt that I will need to use logical operators in the modules in this collection. If I do, I will explain them at the time. However, Iwill use relational operators.

The relational operators that are supported by JavaScript are shown in Figure 7 .

Figure 7 . Relational operators.
>Left operand is greater than right operand>= Left operand is greater than or equal to right operand<Left operand is less than right operand<= Left operand is less than or equal to right operand == Left operand is equal to right operand!= Left operand is not equal to right operand

As with the arithmetic operators discussed earlier, we will use these operators extensively as we work through the physics exercises in futuremodules.

Variables

The next item in the list under Structured programming is repetition . Before I can explain repetition, however, I need to explain the use of variables.

What is a variable?

You can think of a variable as the symbolic name for a pigeonhole in memory where the script can store a value. The script can change the values stored inthat pigeonhole during the execution of the script. Once a value has been stored in a variable, that value can be accessed by calling out the name of thevariable.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
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Source:  OpenStax, Accessible physics concepts for blind students. OpenStax CNX. Oct 02, 2015 Download for free at https://legacy.cnx.org/content/col11294/1.36
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