Vue 3 - Composition Api - Typescript -> type of emit

You need to define your component with the defineComponent method and apply the correct type to props. If you are using single file components it would look something like this

<script lang="ts">
import { defineComponent } from 'vue'
export default defineComponent({
    props: {
        widgetType: {
            type: String,
            required: true
        },
        displayType: {
            type: String,
            required: true
        },
        trigger: {
            type: number,
            required: true
        }
    },

    setup(props, { emit }) {

        // Rest of your setup code here
    }
});
</script>

For example correct typing with component "App" and composable "useModal"

App:

<script lang="ts"> 
 import {defineComponent, SetupContext, ComponentPropsOptions} from 'vue';
 import {useModal} from '@/composable/useModal';
                    
 export default defineComponent({
   name: 'App',
   emits: ['openModal'],
   setup(props: ComponentPropsOptions, {emit}: SetupContext) {
     const openModal = useModal({emit});
                    
     return {openModal};
   }
});
</script>

useModal:

import {SetupContext} from 'vue';

interface UseModalProps {
  emit: SetupContext['emit'];
}

export function useModal({emit}: UseModalProps) {
  function openModal({title, type}: {title: string; type: string}): void {
    emit('openModal', {title, type});
  }

  return {openModal};
}