Monday, August 6, 2018

JS Validations for Input Field Type ‘Number’


Dear Readers,
Sometimes we have need of validation in number type input field in web pages. Main types of validations are :

1)      Drag and drop should be disabled
2)      Input should be only number whether on paste or on input.
3)      Should allow only one dot in the input number if input is decimal

Here, we will take input type=”number” control of HTML. You can use type=”text” as well. Basic benefit of this control is, it provides basic validations automatically. For more details about number type input, CLICKHERE.

Step 1: Create a JS file in your editor, Notepad, Notepad++, Visual Studio Code etc.

Step 2: Write the following code:
Following code will disable the Drag and Drop to the control-
$(':input[type="number"]').attr("ondrop", "return false;");
$(':input[type="number"]').attr("ondrag", "return false;");
Following code will validate the value on keypress of the keyboard.
$(':input[type="number"]').keypress(function (event) {
    // allow only one dot (.) in numeric field (For decimal values)
    // It will also restrict 'e' + - symbols for numeric text boxes because these symbols can be entered by default in input type ‘number’
    if(event.which != 8 && ((event.which != 46 || (event.which == 46 && $(this).val() == '')) ||
            $(this).val().indexOf('.') != -1) && (event.which < 48 || event.which > 57)){
        return false;
    }
});

Step 3: Write the following code for validation on paste of the values
$(':input[type="number"]').on('paste', function () {
   
    var ctrlval = $(this).val();
    var $this = $(this);
    setTimeout(function () {
        if (!$.isNumeric($this.val())) {
            $this.val($this.val().replace(/[^0-9]/g, ''));
            $this.val(ctrlval);
        }
    }, 4);
});

Step 4: Save the file with .JS extension and drag and drop link of this file in your webpage.
For example: <script src="~/JS/CommonJS.js"></script>

I hope it will help. Mail me for any more query. Suggestions/feedbacks are most welcome.

CLICK HERE to subscribe my youtube channel.
Happy Coding.

Rudra Pratap Singh
Software Engineer

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