How to add event listener to input tag and perform some kind of conditions and display something using javascript

Question

I want to read number from input field html if number entered in input field is negative for ex- -5 display "enter a positive number " using javascript
https://code.sololearn.com/WVtdH5HhdhNF/?ref=app

Answer 1

Shelly Kapoor
I said call function on click event. You have to add a button and add click event on that button. And do other operation in that function like get value and check condition.

Answer 2

Shelly Kapoor
Check the spelling of myFunction
var number=document.getElementById("someid");
Write this line inside function and
You are not getting value from this element
There should be if (number.value < 0)
https://code.sololearn.com/WATz0CAH2eLL/?ref=app

Answer 3

Shelly Kapoor
Did you check my shared code?

Answer 4

Shelly Kapoor Check my code again. That is working as you want.
I think you didn't check with different input

Answer 5

Shelly Kapoor make a function and call that function on click event. Perform the task inside that function.

Answer 6

Ipang yes it's fine but how to output the value based on condition outside the input field I have use <p> tag and using document.getElementById.innerHTML I am trying to output but it is not outputing

Answer 7

A͢J ,Ipang https://codepen.io/shelly-kapoor/pen/zYWyMZX I have solved it using event listener but if number is equal to even I want to print 2,4,6 if user type 2,if user type 4, I want 4,6,8

Answer 8

A͢J I want to read value from input tag not onclick when I enter any value it reads That and display something based on condition outside the input field.If possible could you refractor my code.I have made my logic already but needs to read from input field

Answer 9

A͢J please check I have made some changes it is not displaying output "enter a positive number "after reading value from input field

Answer 10

Shelly,
If you want to check as any input was typed in; then "oninput" is probably what you wanted.
https://www.w3schools.com/jsref/event_oninput.asp

Answer 11

Shelly,
First understand that input value is generally a string value, thus we need to convert it into a numeric value using Number()
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number
And then check whether it is a valid numeric data using isNaN()
https://developer.mozilla.org/id/docs/Web/JavaScript/Reference/Global_Objects/isNaN
Once the data is validated, then you can proceed with your own numeric validation - positive/negative, odd/even

Answer 12

And assign some data to an element's innerHTML attribute to change its content
document.getElementById("output").innerHTML = "Enter a positive number";

Answer 13

It is easy in saying can you implement it?

Answer 14

Shelly,
Yes, but I am sure you can do this so don't give up now that you're so close ...

Answer 15

Yes,AJ In it what I want is when you enter input value like -3 it should display at that time exactly outside the box saying "Enter any positive number".So how to do this I think it will not work with function I have to add event listener
https://code.sololearn.com/WRZNGEtFhbBQ/?ref=app