Lightning Web Component

Avoid Using Server side Call(Apex Class) using lightning/uiRecordApi.
For Toast in LWC use lightning/platformShowToastEvent.

Example :

import OBJECT from '@salesforce/schema/ObjectAPIName';

import NAME_FIELD from '@salesforce/schema/ObjectAPIName.FieldAPIName';

ObjectAPIName can be Account/Contact/CustomObject__c
FieldAPIName can be Name (FieldAPIName).
Lwc_DemoComponent.js:

import { LightningElement, track} from 'lwc';

import { createRecord } from 'lightning/uiRecordApi';

import { ShowToastEvent } from 'lightning/platformShowToastEvent';

import OBJECT from '@salesforce/schema/ObjectAPIName';

import NAME_FIELD from '@salesforce/schema/ObjectAPIName.FieldAPIName';

export default class Lwc_DemoComponent extends LightningElement {

    isActive = true;

    @track groupId;

     name = '';

    handleNameChange(event) {

        this.groupId = undefined;

        this.name = event.target.value;

    }

    createRecord() {

        const fields = {};

        fields[NAME_FIELD.fieldApiName] = this.name;

        const recordInput = { apiName: OBJECT.objectApiName, fields };

        createRecord(recordInput)

            .then(taskTeam => {

                this.groupId = taskTeam.id;

                this.dispatchEvent(

                    new ShowToastEvent({

                        title: 'Success',

                        message: 'Group created',

                        variant: 'success',

                    }),

                );

            })

            .catch(error => {

                this.dispatchEvent(

                    new ShowToastEvent({

                        title: 'Error creating record',

                        message: error.body.message,

                        variant: 'error',

                    }),

                );

            });

    }

}

Lwc_DemoComponent.html:

<template>

        <lightning-card title="GroupRecord" icon-name="standard:record">

                <div class="slds-m-around_medium">

                    <lightning-input label="Id" disabled value={groupId}>

</lightning-input>

                    <lightning-input label="Name" onchange={handleNameChange} 

class="slds-m-bottom_x-small"></lightning-input>

                    <lightning-button label="Create Group" variant="brand" 

onclick={createRecord}></lightning-button>

                </div>

         </lightning-card>

</template>