check if string contains only numbers, else show message

Question

I have a simple form, which performs a calculation when a digit is pressed, however this should only happen when numbers are typed, if a letter is added i would like for a notification to appear. Is there a simple function to do this?

Form

    <input onKeyPress="return onlyNumbers()" onKeyUp="calc()" id="value1" type="text" name="value1">
    <select onChange="calc()" id="manipulator" name="manipulator">
        <option value="commission">Commission</option>
        <option value="cost">Return</option>
    </select>
</form>

calc function

function calc(){
    if (window.XMLHttpRequest){// code for IE7+, Firefox, Chrome, Opera, Safari
        xmlhttp=new XMLHttpRequest();
    } else {// code for IE6, IE5
        xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
    }

    val1 = document.getElementById("value1").value;
    mani = document.getElementById("manipulator").value;

    if (val1 != ""){
        document.getElementById("resp").innerHTML="Calculating...";
        queryPath = "comCalcServ.php?value1="+val1+"&manipulator="+mani;

        xmlhttp.onreadystatechange=function(){
            if (xmlhttp.readyState==4 && xmlhttp.status==200){
                document.getElementById("resp").innerHTML=xmlhttp.responseText;
            }
        }

        xmlhttp.open("GET",queryPath);
        xmlhttp.send();
    }
}

I am currently looking at the isNaN function but not familiar with the JS syntax so unsure where to use it.

@DenysSéguret that won't work. Try parseFloat('12xxxx12') in your console and check what that returns :) — Stan Smulders
– Stan Smulders, Commented Sep 9, 2020 at 12:01

Sudhir Bastakoti · Accepted Answer · 2012-04-30 09:04:06Z

7

Do you mean:


//add inside your calc function
val1 = document.getElementById("value1").value;
if(/^\d+$/.test(val1)) {
 //proceed with rest of code
}
else {
 alert("Invalid");
 return false;
}

answered Apr 30, 2012 at 9:04

Sudhir Bastakoti

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1 Comment

Darren Burgess Over a year ago

Stupid question but would this be inserted into the calc function? im unfamiliar with js.

shreedhar bhat · Accepted Answer · 2016-10-06 07:53:16Z

1

Try this simple one

if(val1.match(/^\d+$/)) {
    // your code
}

answered Oct 6, 2016 at 7:53

shreedhar bhat

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Comments

Igbanam · Accepted Answer · 2016-04-11 09:02:06Z

0

the above code did not work in my case . so i made few changes . i just changed regex to /^[0-9]*$/.test(val1) and it worked.

edited Apr 11, 2016 at 9:02

Igbanam

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answered Apr 11, 2016 at 6:46

kaustubh

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2 Comments

Maria Over a year ago

This does not provide an answer to the question. Once you have sufficient reputation you will be able to comment on any post; instead, provide answers that don't require clarification from the asker. - From Review

kaustubh Over a year ago

not having enough reputation doen't mean i am wrong. i just wrote the lines which did my job

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