.attr()

The .attr() method is used to set or get attributes of selected elements. This method is commonly used for styling elements by setting their attributes.

Syntax

selection.attr("attributeName", "attributeValue");

The .attr() function takes two parameters:

• attributeName: Name of the attribute
• attributeValue: Value of the attribute or a callback function.

Example

In the example given below, the value 5 is set to the attribute radius which turns the radius of circle to 5 units:

d3.select('circle').attr('radius', 5);

Output of the above example will be:

![example 1](https://raw.githubusercontent.com/vrun1208/docs/d3-styling-attr/media/d3-styling-attr-example.jpg)

The following example shows how to use the argument as a callback function. Based on the provided data, it is used to compute attribute values dynamically. Here, the circle’s parameter is calculated using the function:

d3.select('circle').attr('parameter', function (d) {
  return 2 * 3.14 * d.radius;
});