bootstrap-vue/es/mixins/form-size.js

BootstrapVue provides one of the most comprehensive implementations of Bootstrap 4 components and grid system for Vue.js and with extensive and automated WAI-ARIA accessibility markup.

export default {
  props: {
    size: {
      type: String,
      default: null
    }
  },
  computed: {
    sizeFormClass: function sizeFormClass() {
      return [this.size ? "form-control-" + this.size : null];
    },
    sizeBtnClass: function sizeBtnClass() {
      return [this.size ? "btn-" + this.size : null];
    }
  }
};