Question

178

How can I check if the input is empty in JavaScript?

rated 0 times [ 185] [ 7] / answers: 1 / hits: 56177 / 9 Years ago, wed, june 3, 2015, 12:00:00

I am trying to make a factorial calculator. How can I check if the input is empty or not? I tried 'null'. But it didn't work or I couldn't use it properly.

sorry for the stupid question. I am newbie in JavaScript

function myFriday() {

  var input = document.getElementById(input1).value;



  var ever = function () {

    if( !(isNaN(input))) {

      var result = 1;

      for(var i = 1; i <= input; i++ ) {

        result = result * i

      }

      return result;

    }

    else if (input == null){

      return Please input a number

    }

    else{

      return Please input a number

    }

  }



  document.getElementById(input2).value = ever();

}

<p>Input: <input type=text id = input1 /></p>

<p>Input: <input type=text id = input2 /></p> 

<button onclick = myFriday()>Calculate</button>

<p >RESULT: <span id = result style = color:red></span> </p>

Answers

Only authorized users can answer the question. Please sign in first, or register a free account.

jeffery

Add To Favorites

Follow

Total Points: 180

Total Questions: 114

Total Answers: 117

Location: Chad

Member since Mon, Dec 5, 2022

2 Years ago

jeffery questions

1 Combine two objects in react, no success so far

Fri, Jan 22, 21, 00:00, 3 Years ago

1 Dynamic import in JS and Vue.js

Wed, Dec 2, 20, 00:00, 4 Years ago

1 Waiting for async function in React component & Showing Spinner

Fri, Jul 31, 20, 00:00, 4 Years ago

1 Node Telegraf callback button

Mon, Apr 13, 20, 00:00, 4 Years ago

1 How to create arrays from array

Mon, Feb 10, 20, 00:00, 4 Years ago

View All

answered 9 Years ago zachary · Accepted Answer

function myFriday() {

  var input = document.getElementById(input1).value;



  var ever = function() {

    if (input.trim() == '') {

      return Please input a number

    } else if (!(isNaN(input))) {

      var result = 1;

      for (var i = 1; i <= input; i++) {

        result = result * i

      }

      return result;

    }



  }



  document.getElementById(input2).value = ever();

}

<p>Input:

  <input type=text id=input1 />

</p>

<p>Input:

  <input type=text id=input2 />

</p>

<button onclick=myFriday()>Calculate</button>

<p>RESULT: <span id=result style=color:red></span> 

</p>