Introduction of JavaScript
JavaScript is most powerful browser based scripting language. Now days it is used an incredible number of high-profile applications.
JavaScript was created in 1995 by Brendan Eich. JavaScript is a dynamic language for its types and operators structure .
Number
String
Boolean
Function
Object (Function, Array, Date RegExp)
Symbol (new in ES2015)
Number
Math.sin() = It gives the numeric number
parseInt() = Convert a string to an integer
parseFloat() = gives floating number (Ignore everything if contain any sign (+, -, .)
NaN = Not a Number
isNaN(‘hello’); // true
isNaN(‘1’); // false
String
For showing or counting single charter we use string.
‘tree’. length (it shows 4)
Other Types
JavaScript has two types of Boolean (‘true’) and (‘false’)
false, 0, empty strings (“”), NaN, null, and undefined all become = false.
Except these all become = true.
Variables
In JavaScript these three keywords of let, const, or var are use to declare ariable:
let x ;
let name = ‘person name’ (for change variable use ‘let’)
const Pi = 3.14 (for fixed vabiable we use ‘const’)
var x ;
var name = ‘person name’ (it does not have any restriction, how will we use whether it is fixed or changeable)
Operators
JavaScript numeric operators are +, -, *, / and remainder operator is %
Comparison Operators
Control structures
if else operator
var name = ‘man’;
if (name === ‘hen’) {
name += ‘ kut-kut’;
} else if (name === ‘man’) {
name += ‘ owa-owa’;
} else {
name += ‘!’;
}
console.log(name);
// man owa owa
if anyone call the variable ‘man’ it answer ‘owa owa’
if anyone call the variable ‘hen’ it answer ‘kut kut’
if anyone call the nothing ‘’ it answer ‘!’
for Loop structure
for (var i = 0; i < 10; i++) {// Loop Will execute 10 times and last value will be 9
}for (var i = 0; i <= 10; i++) {// Loop Will execute 10 times and last value will be 10}
do while loop
var text = “”;
var i = 0;
do {
text += i + “,”;
i++;
}
while (i < 5);
console.log(text);
//0,1,2,3,4,