Is there any way to prevent input type="number" getting negative values?

Use the min attribute like this:

<input type="number" min="0">

For me the solution was:

<input type="number" min="0" oninput="this.value = Math.abs(this.value)">

Edit

As suggested on the comments with a minor change to work if 0 is the min value.

<input type="number" min="0" oninput="this.value = 
 !!this.value && Math.abs(this.value) >= 0 ? Math.abs(this.value) : null">

I was not satisfied with @Abhrabm answer because:

It was only preventing negative numbers from being entered from up/down arrows, whereas user can type negative number from keyboard.

Solution is to prevent with key code:

// Select your input element.
var number = document.getElementById('number');

// Listen for input event on numInput.
number.onkeydown = function(e) {
    if(!((e.keyCode > 95 && e.keyCode < 106)
      || (e.keyCode > 47 && e.keyCode < 58) 
      || e.keyCode == 8)) {
        return false;
    }
}

<form action="" method="post">
  <input type="number" id="number" min="0" />
  <input type="submit" value="Click me!"/>
</form>

Clarification provided by @Hugh Guiney:

What key codes are being checked:

• 95, < 106 corresponds to Numpad 0 through 9;
• 47, < 58 corresponds to 0 through 9 on the Number Row; and 8 is Backspace.

So this script is preventing invalid key from being entered in input.

This code is working fine for me. Can you please check:

<input type="number" name="test" min="0" oninput="validity.valid||(value='');">

Easy method:

<input min='0' type="number" onkeypress="return (event.charCode == 8 || event.charCode == 0) ? null : event.charCode >= 48 && event.charCode <= 57">