Check If Input Is Number JavaScript

Check If Input Is Number JavaScript

by

Check If Input Is Number JavaScript

In this Article i will show you how  to  write the code to check whether the User Input is Number in JavaScript

To Write this Code i will use only one  JavaScript Function

  1. document.getElementById().innerHTML .

To Create This Sample, i will need  few things Setup in HTML

  1. A text Box for the User to input
  2. A Button for the User to Submit the Input

I will create one Function

  1. checkNum(numS) -> This Function will check whether the User has enter a numerical Number

 

Check If Input Is Number JavaScript

Input a Number :

How I code The Above

  1. Create the HTML Structure Doc type,  Head, Body Etc , I attached the code in this Blog , feel free to copy it for your reference
  2. Create the Function Call checkNum(numS)
  3. This Function will check  2 things ( (1) Whether the User enter anything (2) Whether the User Enter a Number
  4. I will Use the isNaN() Function
  5. First i will get the User input using the DOM Function numS = document.getElementById(“createNum”).value;
  6. And Save the Value into variable numS
  7. Then i will use isNaN() to check whether the User Enter a Number  , if isNaN() is True , which means that the User  had Enter a non Numeric Number
  8. Then I will check whether the User had enter anything into the text box !numS

The Code is as Below , Feel Free to copy it For your reference

01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
<!DOCTYPE html>
<html>
<head>
 
<script type="text/javascript">
//This is a New Array
var newArray = [];
 
// This Fuunction push the enter value into the Array
function checkNum(numS){
 
numS = document.getElementById("createNum").value;
 
 
if(isNaN(numS)){
 
 
alert("You did Not enter a Number");
 
}
 
 
else if(!numS) {
 
 
alert("You did Not enter anything");
 
}
 
 
 
 
 
else {
 
alert("You Just Enter a Number");
 
 
}
 
 
}
 
 
 
 
</script>
</head>
<body>
 
<h2>Check If Input Is Number JavaScript</h2>
 
 
<P style="color:blue;"><strong>Input a Number :</strong><input type="text" style="text-align:center; margin-left: 10px;" id="createNum" name="element" placeholder="Input A Number" >
 
 
 
 
 
<p><input type="button" style="text-align:center; margin-left: 10px;" value="Click & Check" id="" onclick="checkNum(this.numS);"/> </P>
 
 
 
 
</body>
 
</html>
 
&nbsp;

There are tonnes of library and tutorial and explanation on this site , you can check out here

 

Check out how to empty an Array in JavaScript here

 

 

 

Leave a Comment

2 × two =