Learn JavaScript Quickly
Introduction: -
Welcome to Learn
JavaScript Quickly tutorial series.
As you know that there are a lot of tutorial there to teach you
Java Script in detail which will take a lot of your time. And you are having
low amount of time to spend. Here you will learn JavaScript Quickly. So without
wasting much time let’s start learning JavaScript Quickly.
JavaScript is a
client side language in website design and development. JavaScript runs in a web
browser. Java script is usually used for client side validation, interaction
with html and many other client side works. In this tutorial of JavaScript
Quickly series you will learn Basic Variables, Loops, Writing on webpage and
displaying messages. One thing to remember is that in this tutorial no HTML
will be included which will make this tutorial easy to learn. We will make HTML
file to run our script only.
Writing something on webpage using JavaScript:-
document.write(); function is used to write anything on web page.
You will pass text to this function to display on document.
Example:-
<script>
document.write(‘Learn
JavaScript Quickly’);
</script>
This save this file as .html and open this in browser. This will
display “Learn JavaScript Quickly”
“<script></script>” are html tags for adding JavaScript
in html document. Always remember to surround your JavaScript with these tags.
You should always add “;” at the end of JavaScript line.
Exercise:-
You should write your name using this function you have learned.
Displaying Messages:-
alert(); function is used to display messages in webpage. You will
pass text to this function to display message box.
Example:-
<script>
alert(“Learn
JavaScript Quickly”);
</script>
Above code will display message “Learn JavaScript Quickly”. Run
this and see result.
Exercise:-
Write your name using alert 3 times.
Basic Variables:-
This section will teach you only basic variables and their usage.
Variable is a section of memory which is reserved for storing any data. To
store anything JavaScript uses var for variable declaration. Syntax of
declaration is var myVar; and value is added as myVar = 10 etc. Here value is
10.
Example1:-
<script>
var myVar;
myVar = 10;
document.write(myVar);
</script>
Example2:-
<script>
var myVar;
myVar = “Learn JavaScript Quickly”;
document.write(myVar);
</script>
In this code myVar is a variable which is used for storing
alphabets and numbers.
Exercise:-
Write your name on document by adding it into a variable. You
should also display message showing value of your variable.
Loops:-
If we want to repeat some set of commands, actions or conditions
loops are used. Syntax is “for(Condition){}”, “while(Condition){}” and
“do{}while(Condition)”. Loop is terminated on certain condition.
Example for Loop:-
<script>
for(var i=0;
i<10; i++)
{
document.write(“Learn
JavaScript Quickly”);
}
</script>
Explanation:-
We have made a variable i and added value of 0 to it. Then checking
i<10;. i++ is used here to increase i by 1. Which will repeat
document.write(“Learn JavaScript Quickly”); 10 times which will display “Learn
JavaScript Quickly” 10 times.
Example while loop:-
<script>
var i = 0;
while(i<10)
{
document.write(“Learn
JavaScript Quickly”);
i++;
}
</script>
Explanation:-
In while loop we can’t make variable, add value to them and
increase them like for loop. We have to declare variable separately check for
condition as while(i<10) then in body we can increase variable like i++.
In this example we have made a variable var i=0; then checked it as
while(i<10) then increased it as i++;. With this document.write(“Learn
JavaScript Quickly”); will be repeated 10 times to display “Learn JavaScript Quickly” 10 times.
Example do while loop:-
<script>
var i = 0;
do
{
document.write(“Learn
JavaScript Quickly”);
i++;
}
while(i<10)
</script>
Explanation:-
This loop works same a while loop. It has one main thing that it
executes at least once. In this example we have created a variable var i=0;
then we have to write do{} to start our do while loop. After body { } we check
for condition of do while loop as while(i<10). In body i will increased as
i++;. When the loop will execute it will repeat document.write(“Learn
JavaScript Quickly”); ten Times to display “Learn JavaScript Quickly” 10 times.
Exercise:-
Display 7 messages box displaying anything using for loop, while
loop and do while loop.
The End
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visiting for more instructive posts.
