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
- document.getElementById().innerHTML .
To Create This Sample, i will need few things Setup in HTML
- A text Box for the User to input
- A Button for the User to Submit the Input
I will create one Function
- 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
- Create the HTML Structure Doc type, Head, Body Etc , I attached the code in this Blog , feel free to copy it for your reference
- Create the Function Call checkNum(numS)
- This Function will check 2 things ( (1) Whether the User enter anything (2) Whether the User Enter a Number
- I will Use the isNaN() Function
- First i will get the User input using the DOM Function numS = document.getElementById(“createNum”).value;
- And Save the Value into variable numS
- 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
- 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
<!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>
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
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