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javascriptparseint

JavaScript parseInt-error

I have an HTML form with a few input-fields, and I want to check that the users enter a number into a text field, instead of a string. I tried this:

if(parseInt(form.width.value) < 0) {
    $("#width").attr('placeholder', 'Please input the desired width of the table.');
}

I have tried with a negative number, a positive number, text, but nothing happends. But whatever I try, the code inside the if statement won't be executed. I simply want to check that the user entered a positive integer.

Solution

  • You need to clear the inputted value, otherwise the placeholder won't be displayed.

    if (parseInt(form.width.value) < 0) {
  $('#width')
    .attr('placeholder', 'Please input the desired width of the table.')
    .val('');
}