Javascript
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Basic
alert/prompt/confirm
alert('Windows Popup text');
prompt('Windows Popup Text and return value entered');
confirm('Display ok and Cancel button and return true or false');
Html Tag
<!DOCTYPE html>
<html>
<head>
<title>Java script Demo</title>
</head>
<body>
<h1>Titre niveau 1</h1>
<script>
alert('your javascript here!');
</script>
<script src="js/app.js"></script>
Variables
var myVariable;
var myVariable = 10;
var myVariable = "some string"; var myVariable = 'some string'; var myVariable = 'it \'s easy';
var myBolean = 10 > 1;
var myOppositeBolean = !myBolean;
var myArray =['PHP','C++','Ruby','JS']
Comparison
- Less: <
- Greater: >
- equal (value): ==
- equal (value and type: ===
- not equal: !=
- undefined: == 'undefined'
- function type of variable
alert(typeof myVariable);
Condition
Logic
- and: &&
- or: ||
if
var cond1 = 1 > 2 && 2 > 3;
var cond2 = 1 < 2 | 10 > 1;
var myVariable2 = 0
if(typeof myVariable = 'undefined') {
alert('This variable has not been declared');
}
if(myVariable2) {
alert('This variable is empty');
}
if(cond1) {
alert('cond1 is true');
} else if(cond2) {
alert ('cond2 is true');
} else {
alert('cond1 and cond2 are false');
}
switch / case
switch(value) {
case 'val1':
alert(' = val1');
break;
case 'val2':
alert(' = val2');
break;
default:
alert('None of previous case')
}
?
alert(( 10 > 1) ? 'true' : 'false');
Loop
while
var myNumber = 1;
while (myNumber <= 10) {
console.log(myNumber);
myNumber++;
}
while (true) {
console.log(myNumber);
if(myNumber ==10 {
break;
}
myNumber++;
}
do
do {
myNumber = parseInt(prompt('Enter a number:'));
} while (isNaN(myNnumber));
console.log(myNumber);
for
for {var myNumber = 0; myNumber < 30; myNumber++) {
console.log(myNumber);
}
Basic validation
var number = parseInt(prompt('Enter a number'));
while(isNaN(number)) {
number = parseInt(prompt('This is not a number: Retry:'));
}
Array
var myArray =['PHP','C++','Ruby','JS']
/* Display the first array value */
alert(myArray[0]);
/* change an array value*/
myArray[2]='C#';
/* Add more array */
myArray.push('HTML', 'CSS');
/* Remove last array */
myArray.pop();
/* Remove first array */
myArray.shift();
/* Search in an Array return -1 if not found*/
var promptText = prompt('enter a programmation language');
alter(myArray.indexOf(promptText));
/* Remove from a specific index (remove 2 array from index 1)*/
myArray.splice(1,2);
/* Replace an array value of a specific index (remove 2 array from index 1 and add 2 value from index 1*/
myArray.splice(1,2, 'C#' ,'Java');