Form Input element for Vue

formInput.vue

<template>
  <div class="input" :class="classList">
    <label for="{{ id }}" class="input__label" @click="activate">{{ label }}<span class="required" v-if="required"> *</span></label>
    <input id="{{ id }}" type="{{ type }}" class="input__input" required="{{ required }}" v-model="value | formatInput" @focus="activate" @blur="deactivate" :value="val"></input>
    <div class="input__error" v-if="hasValue && !isValid" transition="input-error">{{ error }}</div>
  </div>
</template>

<script>
// Helpers.
import { validate } from '../../helpers'



// Component export.
export default {

  /**
   * The initial component data.
   *
   * @return {Object} The component's data.
   */
  data() {
    return {
      active: false,
      value: ''
    }
  },



  /**
   * Passed down properties.
   *
   * @type {Object}
   */
  props: {
    id: {
      type: String,
      required: true
    },
    label: {
      type: String,
      required: true,
      default: 'Label'
    },
    type: {
      type: String,
      default: 'text'
    },
    required: {
      type: Boolean,
      default: false
    },
    val: {
      type: String,
      default: ''
    },
    validation: {
      type: String
    },
    error: {
      type: String
    }
  },



  /**
   * Computed properties.
   *
   * @type {Object}
   */
  computed: {

    /**
     * Generates a list of classes to use on the component.
     *
     * @return {Object} A map of classes to use.
     */
    classList() {
      return {
        'is-active': this.active || this.hasValue,
        'is-valid': this.hasValue && this.isValid,
        'is-invalid': this.hasValue && !this.isValid
      }
    },




    /**
     * Determines if the form field has a value.
     *
     * @return {Boolean} If there's a value or not.
     */
    hasValue() {
      return this.value.length
    },



    /**
     * Determines if the form field is validated.
     *
     * @return {Boolean} If the component is valid or not.
     */
    isValid() {
      let type = this.validation
      let value = this.value

      // Only validate when requested, otherwise assume validation is not
      // required.
      if (type) {
        return validate(type, value)
      } else {
        return !!value
      }

    }

  },



  /**
   * Initialize the component.
   */
  ready() {

    if (this.validation) {

      switch (this.validation) {

        case 'email':
          this.error = 'Format: you@domain.com'
          break

        case 'password':
          this.error = 'Minimum of 8 characters'
          break

        case 'name':
          this.error = 'Minimum of 2 characters'
          break

        case 'address':
          this.error = 'Address error'
          break

        case 'housenumber':
          this.error = 'Housenumer error'
          break

        case 'tel':
          this.error = 'Exactly 10 digits'
          break

        case 'postalcode':
          this.error = 'Format: A1B 2C3'
          break

        case 'text':
          this.error = 'Minimum of 2 characters'
          break

        default:
          this.error = 'Not a valid value'

      }

    }

  },



  /**
   * Component filters.
   *
   * @type {Object}
   */
  filters: {

    /**
     * Formats input elements.
     *
     * @type {Object}
     */
    formatInput: {

      /**
       * Reads the model and outputs the view.
       *
       * @param  {String} val The input value
       * @return {String}     The formatted output.
       */
      read: function(val) {

        let area
        let first
        let second

        switch (this.validation) {

          case 'tel':
            area = val.substr(0, 3)
            first = val.substr(3, 3)
            second = val.substr(6, 4)

            if (area || first || second) {
              val = '(' + area + ') ' + first + ' ' + second
            }

            break

          case 'postalcode':
            first = val.substr(0, 3)
            second = val.substr(3, 3)

            val = first.toUpperCase() + ' ' + second.toUpperCase()
            break

          default:
            break

        }

        return val

      },



      /**
       * Writes the model and reads the view.
       *
       * @param  {String} val The formatted input.
       * @return {String}     The cleaned input.
       */
      write: function(val) {

        switch (this.validation) {

          case 'tel':
            val = val.replace(/\D/gmi, '')
            break

          case 'postalcode':
            val = val.replace(/\s/gmi, '')
            break

          default:
            break

        }

        return val

      }
    }

  },



  /**
   * Component methods.
   *
   * @type {Object}
   */
  methods: {

    /**
     * Activates the form field.
     */
    activate() {
      this.active = true
    },



    /**
     * Deactivates the form field.
     */
    deactivate() {
      this.active = false
    }

  }

}
</script>

<style lang="scss">
@import '../../assets/sass/tools';



.input {
  position: relative;
  margin: $ui-padding 0 ($ui-padding * 2);

  text-align: left;

  font-size: $ui-font-size;

  @include mq('desk') {
    font-size: 14px;
  }
}

.grid__item .input {
  margin: 20px 0 30px;
}

  .input__label {
    display: block;
    width: 100%;
    position: absolute;

    padding: $ui-padding 0;

    color: lighten(color('black'), 50%);
    text-align: left;

    cursor: pointer;

    transition: all .3s ease;

    transform-origin: 0 50%;
  }

  .input__input {
    display: block;
    width: 100%;

    border: 0 solid color('ui');
    border-bottom-width: 1px;

    padding: 10px 0;

    font-size: $ui-font-size;

    // background-color: color('ui-light');

    @include transition('ui');

    &:hover,
    &:focus {
      border-color: color('secondary', 'yellow');
      outline: none;
    }
  }

  .input__error {
    position: absolute;
    top: 105%;
    width: 100%;

    color: color('primary', 'red');
    font-size: $ui-font-size-small;
    text-align: right;
  }

.is-active {

  .input__label {
    padding: 5px 0;

    color: lighten(color('black'), 25%);

    transform: translate(0, -65%) scale(.75);
  }

}

.is-invalid {

  .input__input {
    border-color: color('primary', 'red');
  }

}

// Transitions.
.input-error-transition {
  @include transition('fast', 'opacity, transform');
}

.input-error-enter,
.input-error-leave {
  opacity: 0;
  transform: translate(0, 25%);
}
</style>