Use the dataSource option to bind the widget to a data source, which contains tasks. If the field names in your data source differ from default names ('id', 'parentId', 'title', 'start', 'end', 'progress'), use appropriate options (keyExpr, parentIdExpr, etc.) to map data fields.

jQuery

index.js

data.js

$(function() {
    $("#gantt").dxGantt({
        tasks: {
            dataSource: tasks,
            keyExpr: "taskId", 
            parentIdExpr: "parentTaskId",
            titleExpr: "taskTitle",
            progressExpr: "taskProgress",
            startExpr: "startDate",
            endExpr: "endDate"
        },
        //...
    });
});

var tasks = [{
    'taskId': 1,
    'parentTaskId': 0,
    'taskTitle': 'Software Development',
    'startDate': new Date('2019-02-21T05:00:00.000Z'),
    'endDate': new Date('2019-07-04T12:00:00.000Z'),
    'taskProgress': 31
},
// ...
];

Angular

app.component.html

app.component.ts

app.module.ts

app.service.ts

<dx-gantt ... >
    <dxo-tasks 
        [dataSource]="tasks" 
        keyExpr="taskId"
        parentIdExpr="parentTaskId"
        titleExpr="taskTitle"
        progressExpr="taskProgress"
        startExpr="startDate"
        endExpr="endDate" >
    </dxo-tasks>
    <!-- ... -->
</dx-gantt>

import { Component } from '@angular/core';

@Component({
    selector: 'app-root',
    templateUrl: './app.component.html',
    styleUrls: ['./app.component.css']
})

export class AppComponent {
    tasks: Task[];
    // ...
    constructor(service: Service) {
        this.tasks = service.getTasks();
        // ...
    }        
}

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { AppComponent } from './app.component';
import { DxGanttModule } from 'devextreme-angular';
import { Service, Task, ... } from './app.service';

@NgModule({
    imports: [
        BrowserModule,
        DxGanttModule
    ],
    providers: [Service],
    declarations: [AppComponent],
    bootstrap: [AppComponent]
})
export class AppModule { }

import { Injectable } from '@angular/core';

export class Task {
    taskId: number;
    parentTaskId: number;
    taskTitle: string;
    startDate: Date;
    endDate: Date;
    taskProgress: number;
}

const tasks: Task[] = [{
    'taskId': 1,
    'parentTaskId': 0,
    'taskTitle': 'Software Development',
    'startDate': new Date('2019-02-21T05:00:00.000Z'),
    'endDate': new Date('2019-07-04T12:00:00.000Z'),
    'taskProgress': 31
},
// ...   
]; 
@Injectable()
export class Service {
    getTasks(): Task[] {
        return tasks;
    }
}

Vue

App.vue

data.js

<template>
    <DxGantt ... >        
        <DxTasks
            :data-source="tasks"
            key-expr="taskId"
            parent-id-expr="parentTaskId"
            title-expr="taskTitle"
            progress-expr="taskProgress"
            start-expr="startDate"
            end-expr="endDate" />
        <!-- ... -->
    </DxGantt>
</template>
<script>
    import 'devextreme/dist/css/dx.common.css';
    import 'devextreme/dist/css/dx.light.css'; 

    import { 
        DxGantt, 
        DxTasks, 
        // ... 
    } from 'devextreme-vue/gantt';

    import { 
        tasks, 
        // ... 
    } from './data.js';

    export default {
        components: { 
            DxGantt, 
            DxTasks, 
            // ... 
        },
        data() {
            return { 
                tasks, 
                // ... 
            };
        }
    };
</script>

export const tasks = [{
    'taskId': 1,
    'parentTaskId': 0,
    'taskTitle': 'Software Development',
    'startDate': new Date('2019-02-21T05:00:00.000Z'),
    'endDate': new Date('2019-07-04T12:00:00.000Z'),
    'taskProgress': 31
},
// ...
];

React

App.js

data.js

import React from 'react';

import 'devextreme/dist/css/dx.common.css';
import 'devextreme/dist/css/dx.light.css';

import Gantt, { 
    Tasks, 
    // ... 
} from 'devextreme-react/gantt';
import { 
    tasks, 
    // ... 
} from './data.js';

class App extends React.Component {
    render() {
        return (
            <Gantt ... >
                <Tasks 
                    dataSource={tasks}
                    keyExpr="taskId"
                    parentIdExpr="parentTaskId"
                    titleExpr="taskTitle"
                    progressExpr="taskProgress"
                    startExpr="startDate"
                    endExpr="endDate" />
                {/* ... */}
            </Gantt>
        );
    }
}
export default App;

export const tasks = [{
    'taskId': 1,
    'parentTaskId': 0,
    'taskTitle': 'Software Development',
    'startDate': new Date('2019-02-21T05:00:00.000Z'),
    'endDate': new Date('2019-07-04T12:00:00.000Z'),
    'taskProgress': 31
},
// ...
];