JavaScript alert - prompt - confirm Dialog Boxes
JavaScript alert - Dialog box
Description
alert() is a simple function to display a message to a dialog box (also called alert box). Here is a simple example to display a text in the alert box.
HTML Code
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset=utf-8>
<title>Javascript alert box example-1</title>
</head>
<body>
<h1 style="color: red">JavaScript alert() box example</h1>
<hr />
<script type="text/javascript">
alert("This is a alert box");
</script>
</body>
</html>
View the example in the browser
Let's puts some variables in the alert box.
HTML Code
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset=utf-8>
<title>JavaScript alert box example-2</title>
</head>
<body>
<h1 style="color: red">JavaScript alert() box example</h1>
<hr />
<script type="text/javascript">
mess1='Highest marks in Mathematics : ';
math=99;
alert(mess1+math);
</script>
</body>
</html>
View the example in the browser
JavaScript prompt - Dialog box
Description
The alert() method can not interact with the visitor. To interact with the user we use prompt(), which asks the visitor to input some information and stores the information in a variable.
See the following web document.
HTML Code
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset=utf-8>
<title>JavaScript prompt() example-2</title>
</head>
<body>
<script type="text/javascript">
visiter_name = prompt("Input your name : ")
if(visiter_name != null && visiter_name != "")
alert("Your Name is : "+visiter_name);
else
alert("Blank name ...!")
</script>
</body>
</html>
View the example in the browser
JavaScript confirm - Dialog box
Description
Confirm() displays a dialog box with two buttons, OK and Cancel and a text as a parameter. If the user clicks on OK button, confirm() returns true and on clicking Cancel button, confirm() returns false.
See the following web document.
HTML Code
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset=utf-8>
<title>JavaScript confirm box example </title>
</head>
<body>
<h1 style="color: red">JavaScript confirm() box example</h1>
<hr />
<script type="text/javascript">
mess1='Press Ok to Continue.';
math=99;
x = confirm(mess1);
if (x == true)
{
alert("You have clicked on Ok Button.");
}
else
{
alert("You have clicked on Cancel Button."); }
</script>
</body>
</html>
View the example in the browser
Supported Browser
Internet Explorer 7 | Firefox 3.6 | Google Chrome 7 | Safari 5.0.1 | Opera 10 |
Yes | Yes | Yes | Yes | Yes |
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JavaScript: Tips of the Day
JavaScript: Quick Float to Integer
If you want to convert a float to an integer, you can use Math.floor() , Math.ceil() or Math.round() . But there is also a faster way to truncate a float to an integer using |, the bitwise OR operator.
console.log(23.9 | 0); // Result: 23 console.log(-23.9 | 0); // Result: -23
The behaviour of | varies depending on whether you're dealing with positive or negative numbers, so it's best only to use this shortcut if you're sure.
If n is positive, n | 0 effectively rounds down. If n is negative, it effectively rounds up. To put it more accurately, this operation removes whatever comes after the decimal point, truncating a float to an integer.
You can get the same rounding effect by using ~~, as above, and in fact any bitwise operator would force a float to an integer. The reasons these particular operations work is that - once forced to an integer - the value is left unchanged.
Remove Final Digits
The bitwise OR operator can also be used to remove any amount of digits from the end of an integer. This means we don't have to use code like this to convert between types:
let str = "1553"; Number(str.substring(0, str.length - 1));
Instead, the bitwise OR operator allows us to write:
console.log(1553 / 10 | 0) // Result: 155 console.log(1553 / 100 | 0) // Result: 15 console.log(1553 / 1000 | 0) // Result: 1
Ref: https://bit.ly/3nXQk8a
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