D3.js stack.value() Method

The stack.value() method takes a function that returns the value associated with a key.

Syntax:

stack.value([value_func])

Parameters: This function accepts a single parameter as mentioned above and described below:

value_func: This is a function returning the value associated with the key.

Return Value: This method has no return value.

Example:

HTML

<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <script src=
        "https://d3js.org/d3.v5.min.js">
    </script>
</head>

<body>
    <h1 style="text-align:center; color:green;">
        GeeksforGeeks
    </h1>

    <center>
        <canvas id="gfg" width="200" height="200">
        </canvas>
    </center>

    <script>
        var data = [
            { letter: { a: 3840, b: 1920, c: 960, d: 400 } },
            { letter: { a: 1600, b: 1440, c: 960, d: 400 } },
            { letter: { a: 640, b: 960, c: 640, d: 400 } },
            { letter: { a: 320, b: 480, c: 640, d: 400 } }
        ];

        var stackGen = d3.stack()
            // Defining keys
            .keys(["a", "b", "c", "d"])
            // Defining value function
            .value((obj, key) => obj.letter[key]);

        var stack = stackGen(data);

        console.log(stack);
    </script>
</body>

</html>

Output:

D3.js stack.value() Method

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