my outputs from uki: Javascript

💥 JAVASCRIPT

JavaScript is a dynamic computer programming language. It is lightweight and most commonly used as a part of web pages, whose implementations allow client-side script to interact with the user and make dynamic pages. It is an interpreted programming language with object-oriented capabilities.

💥why use JavaScript

JavaScript is one of the 3 languages all web developers must learn:
   1. HTML to define the content of web pages
   2. CSS to specify the layout of web pages
   3. JavaScript to program the behavior of web pages

💥Where to use Java Script

    💢 In HTML, JavaScript code must be inserted between <script> and </script> tags.

<p id="demo"></p>
<script>
document.getElementById("demo").innerHTML = "My First JavaScript";
</script>

💢Scripts can be placed in the <body>, or in the <head> section of an HTML page, or in both.

       <head> <script>
function myFunction() {
    document.getElementById("demo").innerHTML = "Paragraph changed.";
}
</script>       </head>

<body>
<p id="demo"></p>
<button type="button" onclick="myFunction()">Try it</button>

<script>
function myFunction() {
   document.getElementById("demo").innerHTML = "Paragraph changed.";
}
</script>

</body>


💢 Scripts can also be placed in external files
         external files has some advantages:

It separates HTML and code
It makes HTML and JavaScript easier to read and maintain
Cached JavaScript files can speed up page loads

💥JavaScript can "display" data in different ways

Writing into an HTML element, using innerHTML.
Writing into the HTML output using document.write().
Writing into an alert box, using window.alert().
Writing into the browser console, using console.log().

💥JavaScript syntax is the set of rules, how JavaScript programs are constructed.

💥JavaScript statements are composed of:
Values, Operators, Expressions, Keywords, and Comments.

💥The JavaScript syntax defines two types of values: Fixed values and variable values.
Fixed values are called literals. Variable values are called variables.

💥 Java Script Variables

variables are used to store data values.
JavaScript uses the var keyword to declare variables.
An equal sign is used to assign values to variables.
Eg:
<script>
var x;
x = 6;
document.getElementById("demo").innerHTML = x;
</script>

💢 The values can be of various types, such as numbers and strings.
Eg: "John" + " " + "Doe", evaluates to "John Doe"

💥Java Script Comments

Code after double slashes // or between /* and */ is treated as a comment

💥JavaScript is Case Sensitive

All JavaScript identifiers are case sensitive.
The variables lastName and lastname, are two different variables.
Eg:
<script>
var lastname, lastName;
lastName = "Doe";
lastname = "Peterson";
document.getElementById("demo").innerHTML = lastName;
</script>

out put: Doe

💥Java Script is Camel Case

Hyphens

first-name, last-name, master-card, inter-city.

👱 Hyphens are not allowed in JavaScript. It is reserved for subtractions.

Underscore
first_name, last_name, master_card, inter_city.

Upper Camel Case
FirstName, LastName, MasterCard, InterCity.

Lower Camel Case
use camel case that starts with a lowercase letter
firstName, lastName, masterCard, interCity.

my outputs from uki

Tuesday, May 23, 2017

Javascript