I am new to Vue.js. I want an input field which accepts only numeric numbers and if the user enters any other value it will be replace with the empty string. Therefore, I want to add a custom directive to this field viz 'numericOnly'.

Code for custom directive :

Vue.directive('numericOnly', {
  bind (el, binding, vnode) {
    regex = /^[0-9]*$/
    if(!regex.test(el.value)){
     el.value = el.value.slice(0, -1)
    }
  }
})

Here is my template :

<input v-numericOnly name="mobileNumber" placeholder="Mobile Number" >

But it runs only the one time when the input field is bound to the DOM.

Please help me figure out this problem. Thank you in advance.

I am new to Vue.js. I want an input field which accepts only numeric numbers and if the user enters any other value it will be replace with the empty string. Therefore, I want to add a custom directive to this field viz 'numericOnly'.

Code for custom directive :

Vue.directive('numericOnly', {
  bind (el, binding, vnode) {
    regex = /^[0-9]*$/
    if(!regex.test(el.value)){
     el.value = el.value.slice(0, -1)
    }
  }
})

Here is my template :

<input v-numericOnly name="mobileNumber" placeholder="Mobile Number" >

But it runs only the one time when the input field is bound to the DOM.

Please help me figure out this problem. Thank you in advance.

• javascript
• vue.js
• vuejs2

3 Answers 3

Your directive should listen keyup of the input element to achieve what you need:

Vue.directive('numericOnly', {
  bind(el) {
    el.addEventListener('keyup', () => {
      let regex = /^[0-9]*$/
      if (!regex.test(el.value)) {
        el.value = el.value.slice(0, -1)
      }
    })
  }
})

import Vue from 'vue'    
Vue.directive('numericOnly', {
bind(el, binding, vnode) {
    el.addEventListener('keydown', (e) => {
        if ([46, 8, 9, 27, 13, 110, 190].indexOf(e.keyCode) !== -1 ||
            // Allow: Ctrl+A
            (e.keyCode === 65 && e.ctrlKey === true) ||
            // Allow: Ctrl+C
            (e.keyCode === 67 && e.ctrlKey === true) ||
            // Allow: Ctrl+X
            (e.keyCode === 88 && e.ctrlKey === true) ||
            // Allow: home, end, left, right
            (e.keyCode >= 35 && e.keyCode <= 39)) {
            // let it happen, don't do anything
            return
        }
        // Ensure that it is a number and stop the keypress
        if ((e.shiftKey || (e.keyCode < 48 || e.keyCode > 57)) && (e.keyCode < 96 || e.keyCode > 105)) {
            e.preventDefault()
        }
    })
}

})

Updated on Nov 26th 2024:

The event.keyCode property is deprecated

We should use event.key or event.code

// directives/numeric-only.js
export default {
  bind(el) {
    el.addEventListener('keydown', function (event) {
      // Allow control keys such as backspace, delete, arrows, etc.
      if (
        event.key === 'Backspace' ||
        event.key === 'Delete' ||
        event.key === 'ArrowLeft' ||
        event.key === 'ArrowRight' ||
        event.key === 'Tab' ||
        event.key === 'Enter' ||
        (event.ctrlKey && event.key === 'a') || // Allow Ctrl+A (Select All)
        (event.ctrlKey && event.key === 'c') || // Allow Ctrl+C (Copy)
        (event.ctrlKey && event.key === 'v') || // Allow Ctrl+V (Paste)
        (event.ctrlKey && event.key === 'x') // Allow Ctrl+X (Cut)
      ) {
        return; // Do not prevent default for these keys
      }

      // Allow numeric characters only
      if (!/^[0-9]$/.test(event.key)) {
        event.preventDefault(); // Prevent input if not a numeric character
      }
    });
  }
};