Is there any way to prevent input type=“number” ge

问题:

I want to get only positive values, is there any way to prevent it using only html
Please don't suggest validation method

回答1:

Use the min attribute like this:

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

回答2:

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.

回答3:

For me the solution was:

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

回答4:

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

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

回答5:

Easy method:

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

回答6:

The @Manwal answer is good, but i like code with less lines of code for better readability. Also i like to use onclick/onkeypress usage in html instead.

My suggested solution does the same: Add

min="0" onkeypress="return isNumberKey(event)"

to the html input and

function isNumberKey(evt){
    var charCode = (evt.which) ? evt.which : event.keyCode;
    return !(charCode > 31 && (charCode < 48 || charCode > 57));
}

as a javascript function.

As said, it does the same. It's just personal preference on how to solve the problem.

回答7:

Just for reference: with jQuery you can overwrite negative values on focusout with the following code:

$(document).ready(function(){
    $("body").delegate('#myInputNumber', 'focusout', function(){
        if($(this).val() < 0){
            $(this).val('0');
        }
    });
});

This does not replace server side validation!

回答8:

Here's an angular 2 solution:

create a class OnlyNumber

import {Directive, ElementRef, HostListener} from '@angular/core';

@Directive({
  selector: '[OnlyNumber]'
})
export class OnlyNumber {

  // Allow decimal numbers. The \. is only allowed once to occur
  private regex: RegExp = new RegExp(/^[0-9]+(\.[0-9]*){0,1}$/g);

  // Allow key codes for special events. Reflect :
  // Backspace, tab, end, home
  private specialKeys: Array<string> = ['Backspace', 'Tab', 'End', 'Home'];

  constructor(private el: ElementRef) {
  }

  @HostListener('keydown', ['$event'])
  onKeyDown(event: KeyboardEvent) {
    // Allow Backspace, tab, end, and home keys
    if (this.specialKeys.indexOf(event.key) !== -1) {
      return;
    }

    // Do not use event.keycode this is deprecated.
    // See: https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/keyCode
    let current: string = this.el.nativeElement.value;
    // We need this because the current value on the DOM element
    // is not yet updated with the value from this event
    let next: string = current.concat(event.key);
    if (next && !String(next).match(this.regex)) {
      event.preventDefault();
    }
  }
}

add OnlyNumber to declarations in app.module.ts and use like it like this anywhere in your app

<input OnlyNumber="true">

回答9:

<input type="number" name="credit_days" pattern="[^\-]+" 
    #credit_days="ngModel" class="form-control" 
    placeholder="{{ 'Enter credit days' | translate }}" min="0" 
    [(ngModel)]="provider.credit_days"
    onkeypress="return (event.charCode == 8 || event.charCode == 0 || 
    event.charCode == 13) ? null : event.charCode >= 48 && event.charCode <= 
    57" onpaste="return false">

回答10:

I wanted to allow decimal numbers and not clear the entire input if a negative was inputted. This works well in chrome at least:

<input type="number" min="0" onkeypress="return event.charCode != 45">

回答11:

This solution allows all keyboard functionality including copy paste with keyboard. It prevents pasting of negative numbers with the mouse. It works with all browsers and the demo on codepen uses bootstrap and jQuery. This should work with non english language settings and keyboards. If the browser doesn't support the paste event capture (IE), it will remove the negative sign after focus out. This solution behaves as the native browser should with min=0 type=number.

Markup:

<form>
  <input class="form-control positive-numeric-only" id="id-blah1" min="0" name="nm1" type="number" value="0" />
  <input class="form-control positive-numeric-only" id="id-blah2" min="0" name="nm2" type="number" value="0" />
</form>

Javascript

$(document).ready(function() {
  $("input.positive-numeric-only").on("keydown", function(e) {
    var char = e.originalEvent.key.replace(/[^0-9^.^,]/, "");
    if (char.length == 0 && !(e.originalEvent.ctrlKey || e.originalEvent.metaKey)) {
      e.preventDefault();
    }
  });

  $("input.positive-numeric-only").bind("paste", function(e) {
    var numbers = e.originalEvent.clipboardData
      .getData("text")
      .replace(/[^0-9^.^,]/g, "");
    e.preventDefault();
    var the_val = parseFloat(numbers);
    if (the_val > 0) {
      $(this).val(the_val.toFixed(2));
    }
  });

  $("input.positive-numeric-only").focusout(function(e) {
    if (!isNaN(this.value) && this.value.length != 0) {
      this.value = Math.abs(parseFloat(this.value)).toFixed(2);
    } else {
      this.value = 0;
    }
  });
});

回答12:

oninput="this.value=(this.value   < Number(this.min) || this.value   > Number(this.max))  ? '' : this.value;"

回答13:

Here is a solution that worked best of me for a QTY field that only allows numbers.

// Only allow numbers, backspace and left/right direction on QTY input
    if(!((e.keyCode > 95 && e.keyCode < 106) // numpad numbers
        || (e.keyCode > 47 && e.keyCode < 58) // numbers
        || [8, 9, 35, 36, 37, 39].indexOf(e.keyCode) >= 0 // backspace, tab, home, end, left arrow, right arrow
        || (e.keyCode == 65 && (e.ctrlKey === true || e.metaKey === true)) // Ctrl/Cmd + A
        || (e.keyCode == 67 && (e.ctrlKey === true || e.metaKey === true)) // Ctrl/Cmd + C
        || (e.keyCode == 88 && (e.ctrlKey === true || e.metaKey === true)) // Ctrl/Cmd + X
        || (e.keyCode == 86 && (e.ctrlKey === true || e.metaKey === true)) // Ctrl/Cmd + V
    )) {
        return false;
    }