-- oops language
class Employee {
// instance variable
// methods / function
}
-- javascript
function Employee(empid, name) {
this.empid = empid;
this.name = name;
}
// this is possible - es6
class Employee {
int empid; // nooo
constructor(empid, name) {
this.empid = empid;
this.name = name;
}
}
- in javascript constructor is called constructor only you cannot have class name this is valid in java, c++, python....
- in javascript there is no concept of overloading
function hi() {}
function hi(name) {}
function hi(empid, name) {} - overrite
hi();
hi("Abdulla");
hi(101, "Abdulla");
- transpiler
// before running the transpiler
height = height ?? 100;
// after running the transpiler
height = (height !== undefined && height !== null) ? height : 100;
-
java - but it has thick wrapper
-
python - is also same as java + script type
-
javascrpit - scripting language, no compilation, it definately takes time and unpretected
-
php - web application develop
-
'C' - to become very very very fast
-
hoisting
fnAdd(10,20)
function fnAdd(x, y) {
return x + y;
}
// in arrow style
let fnAdd = (x, y) => {
return x + y;
}
// better style
// in arrow style, since its function last statement is always returned
let fnAdd = (x, y) => x + y;
-- callback
function divide(n1, n2, callback) {
if (typeof callback != 'function') {
throw "Callback should be a function or you did not pass";
}
setTimeout(() => {
if (typeof n1 != 'number') {
callback("Please Enter first arg as number");
return;
}
if (typeof n2 != 'number') {
callback("Please enter second arg as number");
return;
}
if (n2 === 0) {
callback("Pls dont divide by zero");
return;
}
callback(null, n1 / n2);
}, 0);
}
- scoping
{
int x;
{
int y;
print x
}
{
int z;
print x;
print y; does not work
}
}
function f1 (val1) {
function f2 (val2) {
val2 is valid
val1 is also valid
}
}
- modules
<html>
<head>
<script scr="./script/script.js"></script>
<script scr="./script/script.js"></script>
<script scr="./script/script.js"></script>
<script scr="./script/script.js"></script>
<script scr="./script/script.js"></script>
<script scr="./script/script.js"></script>
<script scr="./script/script.js"></script>
</head>
<body>
</body>
</html>
- script
- script.js
function hi() {
}
- Links
- es6
- mock server json-server
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