Javascript: Difference between revisions
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| Line 53: | Line 53: | ||
cond1 = 1 > 2 && 2 > 3 | cond1 = 1 > 2 && 2 > 3 | ||
cond2 = 1 < 2 | 10 > 1 | cond2 = 1 < 2 | 10 > 1 | ||
if(typeof myVariable = 'undefined') { | |||
alert('This variable has not been declared'); | |||
} | |||
if(cond1) { | if(cond1) { | ||
alert('cond1 is true'); | alert('cond1 is true'); | ||
Revision as of 14:38, 29 October 2017
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;
Comparison
- Less: <
- Greater: >
- equal (value): ==
- equal (value and type: ===
- not equal: !=
- undefined: == 'undefined'
- function type of variable
alert(typeof myVariable);
Condition
- and: &&
- or: ||
cond1 = 1 > 2 && 2 > 3
cond2 = 1 < 2 | 10 > 1
if(typeof myVariable = 'undefined') {
alert('This variable has not been declared');
}
if(cond1) {
alert('cond1 is true');
} else if(cond2) {
alert ('cond2 is true');
} else {
alert('cond1 and cond2 are false');
}