How to Create a Simple Gantt Chart Using JavaScript
By: Alfrick Opidi
Tags: JavaScript, Project Management, Charts, Gantt Chart, Data Visualization

Creating a JS Gantt chart in 4 steps

Let’s get our hands dirty and use the JavaScript library to create a simple Gantt chart for scheduling and monitoring project activities.

In this JS charting tutorial, we’ll follow these four steps:

Step 1: Preparing the data

Preparing the data Step 2: Getting dependencies

Getting dependencies Step 3: Declaring the chart container

Declaring the chart container Step 4: Rendering the Gantt chart

Step 1: Preparing the data

The first step in building a Gantt chart using JavaScript is to prepare the data that will be displayed. The AnyChart library requires data to be represented using the tree data model.

In this model, the data is organized as a hierarchical tree-like structure in which parent-child relationships are used to connect the various data items.

As such, the parent data item will have a children data field in which the child items are stated as an array.

Let me show you an example of what I’m talking about:

var data = [{

id: "1",

name: "Development Life Cycle",

actualStart: Date.UTC(2018, 01, 02),

actualEnd: Date.UTC(2018, 06, 15),

children: [{

id: "1_1",

name: "Planning",

actualStart: Date.UTC(2018, 01, 02),

actualEnd: Date.UTC(2018, 01, 22),

connectTo: "1_2",

connectorType: "finish-start",

progressValue: "75%"

},

// more data goes here

]

}];

Step 2: Getting dependencies

AnyChart utilizes a minimalist, modular-based approach that lets you get only those dependencies that are essential for your project, which greatly shrinks the size of the deployed code, leading to enhanced performance.

For creating the Gantt chart, we’ll add the following Core and Gantt modules in the <head> section of our web page.

<head>

<script src="https://cdn.anychart.com/releases/8.6.0/js/anychart-core.min.js"> </script>

<script src ="https://cdn.anychart.com/releases/8.6.0/js/anychart-gantt.min.js"></script>

</head>

Step 3: Declaring the chart container

Then, let’s create a container where the Gantt chart will load to.

<body> <div id= " container " ></div> <body>

Notice that I’ve given the <div> element and id of “container” to be referenced in the next step.

Step 4: Rendering the Gantt chart

Lastly, we’ll follow these steps to render the Gantt chart:

Create the data tree by passing the prepared data to the anychart.data.tree() method. For the second parameter, we’ll specify it as “as-tree”.

var treeData = anychart.data.tree(data, " as-tree " );

Create the project Gantt chart by calling the anychart.ganttProject() chart constructor:

var chart = anychart.ganttProject();

Set the data by passing the created data tree to the chart’s data() method:

chart.data(treeData);

Configure the timeline’s scale up to the date that the project will end:

chart.getTimeline().scale().maximum(Date.UTC(2018, 06, 30));

Reference the chart container id we’d set previously:

chart.container("container");

Initiate drawing the chart:

chart.draw();

Fitt the specified activities within the width of the timeline:

chart.fitAll();

Here is the entire code I used for creating the Gantt chart on the picture above:

(You can also view the code on this CodePen repository).

<html>

<head>

<script src="https://cdn.anychart.com/releases/8.6.0/js/anychart-core.min.js"> </script>

<script src ="https://cdn.anychart.com/releases/8.6.0/js/anychart-gantt.min.js"></script>

</head> <body> <div id = "container" > </div> <script> anychart.onDocumentReady(function () {

// create data

var data = [{

id: "1",

name: "Development Life Cycle",

actualStart: Date.UTC(2018, 01, 02),

actualEnd: Date.UTC(2018, 06, 15),

children: [{

id: "1_1",

name: "Planning",

actualStart: Date.UTC(2018, 01, 02),

actualEnd: Date.UTC(2018, 01, 22),

connectTo: "1_2",

connectorType: "finish-start",

progressValue: "75%"

},

{

id: "1_2",

name: "Design and Prototyping",

actualStart: Date.UTC(2018, 01, 23),

actualEnd: Date.UTC(2018, 02, 20),

connectTo: "1_3",

connectorType: "start-start",

progressValue: "60%"

},

{

id: "1_3",

name: "Evaluation Meeting",

actualStart: Date.UTC(2018, 02, 23),

actualEnd: Date.UTC(2018, 02, 23),

connectTo: "1_4",

connectorType: "start-start",

progressValue: "80%"

},

{

id: "1_4",

name: "Application Development",

actualStart: Date.UTC(2018, 02, 26),

actualEnd: Date.UTC(2018, 04, 26),

connectTo: "1_5",

connectorType: "finish-finish",

progressValue: "90%"

},

{

id: "1_5",

name: "Testing",

actualStart: Date.UTC(2018, 04, 29),

actualEnd: Date.UTC(2018, 05, 15),

connectTo: "1_6",

connectorType: "start-finish",

progressValue: "60%"

},

{

id: "1_6",

name: "Deployment",

actualStart: Date.UTC(2018, 05, 20),

actualEnd: Date.UTC(2018, 05, 27),

connectTo: "1_7",

connectorType: "start-finish",

progressValue: "100%"

},

{

id: "1_7",

name: "Maintenance",

actualStart: Date.UTC(2018, 05, 30),

actualEnd: Date.UTC(2018, 06, 11),

progressValue: "40%"

},



]

}];

// create a data tree

var treeData = anychart.data.tree(data, "as-tree");



// create a chart

var chart = anychart.ganttProject();



// set the data

chart.data(treeData); // configure the scale

chart.getTimeline().scale().maximum(Date.UTC(2018, 06, 30)); // set the container id

chart.container("container"); // initiate drawing the chart

chart.draw(); // fit elements to the width of the timeline

chart.fitAll();

}); </script>

</body>

</html>

Customizing the Gantt chart design

AnyChart provides a wide range of options to customize the design of data visualizations to suit your individual preferences and needs. In the data fields, you can set various attributes to customize the look and feel of your Gantt chart.

For example, here are some data fields I specified in the above Gantt chart example:

id — sets the unique identifier of every task;

— sets the unique identifier of every task; name — sets the name of every task;

— sets the name of every task; actualStart — sets the start date of every task;

— sets the start date of every task; actualEnd — sets the end date of every task;

— sets the end date of every task; connectTo — is a type of connector that sets the target task;

— is a type of connector that sets the target task; connectorType — sets the type of connector, which can be “start-start,” “start-finish,” “finish-start,” or “finish-finish”;

— sets the type of connector, which can be “start-start,” “start-finish,” “finish-start,” or “finish-finish”; progressValue — sets the progress value of every task as a percentage.

Furthermore, AnyChart allows the following types of tasks, which can be visualized in different ways:

regular tasks — do not have relationships with other tasks;

— do not have relationships with other tasks; parent tasks — have parent-child relationships with other tasks;

— have parent-child relationships with other tasks; milestones — visualize events with zero duration. They can be specified by setting the same date on the actualStart and actualEnd fields.

Loading data as a table

If you want to create a chart by loading data from a relational database, you can organize the data as a table with parent/child links.

In that case, the parent field of every item should have the id value of its parent specified. Also, you should set the parent of a root item to null, or just fail to specify it.

Here is what I’m talking about:

(You can also view the code on this CodePen repository).

var data = [{

id: 1,

parent: null,

name: "Root",

actualStart: Date.UTC(2018, 01, 02),

actualEnd: Date.UTC(2018, 06, 15),

},

{

id: 2,

parent: 1,

name: "Parent 1",

actualStart: Date.UTC(2018, 01, 02),

actualEnd: Date.UTC(2018, 01, 22),

progressValue: "90%"

},

{

id: 3,

parent: 2,

name: "Child 1–1",

actualStart: Date.UTC(2018, 01, 23),

actualEnd: Date.UTC(2018, 02, 20),

progressValue: "75%"

},

{

id: 4,

parent: 2,

name: "Child 1–2",

actualStart: Date.UTC(2018, 02, 23),

actualEnd: Date.UTC(2018, 02, 23),

progressValue: "60%"

},

{

id: 5,

parent: 1,

name: "Parent 2",

actualStart: Date.UTC(2018, 02, 26),

actualEnd: Date.UTC(2018, 04, 26),

progressValue: "80%"

},

{

id: 7,

parent: 6,

name: "Child 2–1",

actualStart: Date.UTC(2018, 04, 29),

actualEnd: Date.UTC(2018, 05, 15),

progressValue: "30%"

},

];

Also, when you load data as a table, don’t forget to change the second parameter in the anychart.data.tree() method from”as-tree” to “as-table”, so the whole line looks as follows:

var treeData = anychart.data.tree(data, "as-table");

Here is a screenshot of the Gantt chart created when data is loaded as a table: