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Javascripts. pptt
- 2. INTRODUCTION JavaScript isa scripting language with first class functioning. Is originally designed for the browser. It has nothing to do with java. Enhance the interaction of a user with the webpage.
- 3. Was developedby Brendan Eich in 1995. The language was initially called livescript and was later renamed javascript. First version was created in 10 days. It’s the most popular language on Github.
- 4. Uses of javascript In The Browser Used in making modern webpage/web app. Desktop Windows 8 metro UI was built using it. IOT JS is becoming the go to language. Real Time Launches chat built filly in node.
- 5. What Can JSDo Today? Run a VM inside a browser. Run a game inside the browser. Serve 300 million users without shooting up the cpu. Help in making power point presentation online. Make real time chat possible.
- 6. ABILITIES POSSESED BYJS Asynchronous Programming Functional Programming Writing cross-browser code Efficient memory management
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- 11. DATATYPES NUMBER- Hasdouble precision 64 bit format and uses arithmetic and math operations. STRINGS - It supports any language and has many built in functions and properties. BOOLEAN- Coerce any thing into Boolean using Boolean(). NULL - It is an assignment value and is used in absence of value of a variable. UNDEFINED - If a variable is declared but is not assigned a value then it has a undefined data type.
- 12. OBJECTS MOST IMPORTANT PARTOF JS.EVERYTHING IN AN OBJECT IS JS. FUNCTION – All functions have access to special parameters insides its body like arguments etc. ARRAYS – Special type of objects has a special property called length . It is one more than the highest index of array.
- 13. OBJECTS DATE –Exact replica of java date class, lots of date manipulation function inbuilt. Also lots of good i18n function. Reg Exp – Known as regular expression is one of the least exploited part of javascript and is good for form validation.
- 14. Flow Control JS supportsalmost every flow control structure. • If then else • while • For • Switch case • Break • Continue
- 15. ERROR HANDLING One ofthe best way to handle errors is to write a perfect code. Another best option is to make use of try catches. try{ Block of code to try } catch(err){ Block of code to handle errors } This ensures that the rest of the code continues to execute.
- 16. SCOPE Scope is theset of the variables you have access to. In JS there are mainly two scopes. • Local Scope • Global Scope Any variable declared inside a function using var keyword Has a local scope. Any variable declared outside it has global scope. *Special Case :Any variable declared inside a function without the “var” keyword is assumed global and is assigned to global scope. This special case is called Automatic Global.
- 18. Document Object Model The document object represents the whole html document. When html document is loaded in the browser, it becomes a document object. It is the root element that represents the html document. It has properties and methods. By the help of document object, we can add dynamic content to our web page. As mentioned earlier, it is the object of window We can access and change the contents of document by its methods.
- 19. DOM MANIPULATION The DocumentObject Model (DOM) represents that same document so it can be manipulated. The DOM is an object-oriented representation of the web page, which can be modified with a scripting language such as JavaScript. The W3C DOM and WHATWG DOM standards are implemented in most modern browsers.
- 21. JS ON SERVER Node.js,often referred to as just Node, is a powerful tool that can run JavaScript applications on both the server side as well as the client side. Node.js can be used to write static file servers, Web application frameworks, messaging middleware, and servers for HTML5 multiplayer games.