compare two input values in input validation html javascript?

Question

I want to compare two inputs minimumN and maximumN, and display an alert if the logic is not satisfied, I have the following code:

HTML:

<table>
    <tr>
        <th>Minimum N</th>
        <td>
            <input id="minN" onkeyup="MinimumNValidate()" type="text" maxlength="50">
        </td>
        <th>Maximum N</th>
        <td>
            <input id="maxN" onkeyup="MaximumNValidate()" type="text" maxlength="50">
        </td>
    </tr>
</table>

Javascript:

function MinimumNValidate() {
    var min = document.getElementById("minN").value;
    var max = document.getElementById("maxN").value;
    if (min > max) {
        alert("Minimum value must be lesser than maximum value.");
    }
}

function MaximumNValidate() {
    var min = document.getElementById("minN").value;
    var max = document.getElementById("maxN").value;
    if (max < min) {
        alert("Maximum value must be greater than minimum value.");
    }
}

but this is not working, and the alert is being displayed even when the minN is less than maxN, can you point out the mistake in my code ?

This question appears to be off-topic because it is about a typo — rlemon
– rlemon, Commented Sep 20, 2013 at 20:03
It is not a typo, it is parse Int issue but yes.. it has a typo there. — porfiriopartida
– porfiriopartida, Commented Sep 20, 2013 at 20:08
It's a simple typo, but really, off-topic / not about programming? — pawel
– pawel, Commented Sep 20, 2013 at 20:09
sorry about the typo, i have corrected the typo, but still it doesn't seem to be working, can you help ? — Sachin
– Sachin, Commented Sep 20, 2013 at 20:13
@Sachin Can you tell us which inputs are causing the fail? I bet it is a parseInt issue, try this for both validation methods: var min = parseInt(document.getElementById("minN").value); var max = parseInt(document.getElementById("maxN").value); — porfiriopartida
– porfiriopartida, Commented Sep 20, 2013 at 20:13

porfiriopartida · Accepted Answer · 2013-09-20 20:35:15Z

4

Few things here

close the input elements:

if(maxN<min) {

Should be

if(max<min) {

Finally, you are not comparing integers but strings so..

5<9
555<9
1000<20

Its "alphabetic"

You need to parse them to int.

parseInt(max) and parseInt(min)

...

function MinimumNValidate(){
       var min = parseInt(document.getElementById("minN").value);
       var max = parseInt(document.getElementById("maxN").value);
       if(min > max) {
           alert("Minimum value must be lesser than maximum value. " + min + " > " + max );
       } 
 }    

    function MaximumNValidate(){
       var min = parseInt(document.getElementById("minN").value);
       var max = parseInt(document.getElementById("maxN").value);
       if(max<min) {
           alert("Maximum value must be greater than minimum value."  + min + " > " + max );
       } 
  }

answered Sep 20, 2013 at 20:35

porfiriopartida

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Comments

Bradley Bossard · Accepted Answer · 2013-09-20 20:02:29Z

3

In the second function MaximumNValidate(), you have the line of code

if(maxN<min) {

which should be

if(max<min) {

answered Sep 20, 2013 at 20:02

Bradley Bossard

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4 Comments

pawel Over a year ago

+1, but it's annoying as hell ;) jsfiddle.net/FyAnR (@Sachin, use onchange or add some more checks);

Sachin Over a year ago

even after that, i am getting the same output, is the logic correct ?

pawel Over a year ago

@Sachin, the output is correct, but ''<1, so it alerts before you even start to type the max value. Same for typing 100 (three alerts!) in the min, and then typing the max 1 then 0 (two alerts!) then `1' (no alert).

Sachin Over a year ago

i have used the onchange event, the number of alerts have decreased.

medico practolytics · Accepted Answer · 2019-11-20 14:48:49Z

1

function checknumber(theForm) {   
 if (parseInt(theForm.num2.value) != (parseInt(theForm.num1.value)+1)) 
    { 
    alert('enter the correct year in intermediate');
            return false;
            } 
     return true;
            
}

<!doctype html>
<head> </head> 
    <body> 
        <form action="../" onsubmit="return checknumber(this);">     
<label> tenth graduation </label> 
      <input type="number" name="num1"  autocomplete="off"><br> <br>
<label> Intermediate </label>
       <input type="number" name="num2" autocomplete="off">
     <input type="SUBMIT" value="year validation">
       </form>

answered Nov 20, 2019 at 14:48

medico practolytics

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