asciichart

Console ASCII line charts in pure Javascript (for NodeJS and browsers) with no dependencies.

Usage

NodeJS

npm install asciichart

var asciichart = require ('asciichart')
var s0 = new Array (120)
for (var i = 0; i < s0.length; i++)
    s0[i] = 15 * Math.sin (i * ((Math.PI * 4) / s0.length))
console.log (asciichart.plot (s0))

Browsers

<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
        <meta charset="UTF-8">
        <title>asciichart</title>
        <script src="asciichart.js"></script>
        <script type="text/javascript">
            var s0 = new Array (120)
            for (var i = 0; i < s0.length; i++)
                s0[i] = 15 * Math.sin (i * ((Math.PI * 4) / s0.length))
            console.log (asciichart.plot (s0))
        </script>
    </head>
    <body>
    </body>
</html>

Options

The width of the chart will always equal the length of data series. The height and range are determined automatically.

var s0 = new Array (120)
for (var i = 0; i < s0.length; i++)
    s0[i] = 15 * Math.sin (i * ((Math.PI * 4) / s0.length))
console.log (asciichart.plot (s0))

The output can be configured by passing a second parameter to the plot (series, config) function. The following options are supported:

var config = {

    offset:  3,          // axis offset from the left (min 2)
    padding: '       ',  // padding string for label formatting (can be overridden)
    height:  10,         // any height you want

    // the label format function applies default padding
    format:  function (x, i) { return (padding + x.toFixed (2)).slice (-padding.length) }
}

Scale To Desired Height

var s = []
for (var i = 0; i < 120; i++)
    s[i] = 15 * Math.cos (i * ((Math.PI * 8) / 120)) // values range from -15 to +15
console.log (asciichart.plot (s, { height: 6 }))     // this rescales the graph to ±3 lines

Auto-range

var s2 = new Array (120)
s2[0] = Math.round (Math.random () * 15)
for (i = 1; i < s2.length; i++)
    s2[i] = s2[i - 1] + Math.round (Math.random () * (Math.random () > 0.5 ? 2 : -2))
console.log (asciichart.plot (s2))

Multiple Series

var s2 = new Array (120)
s2[0] = Math.round (Math.random () * 15)
for (i = 1; i < s2.length; i++)
    s2[i] = s2[i - 1] + Math.round (Math.random () * (Math.random () > 0.5 ? 2 : -2))

var s3 = new Array (120)
s3[0] = Math.round (Math.random () * 15)
for (i = 1; i < s3.length; i++)
    s3[i] = s3[i - 1] + Math.round (Math.random () * (Math.random () > 0.5 ? 2 : -2))

console.log (asciichart.plot ([ s2, s3 ]))

Colors

var arr1 = new Array (120)
arr1[0] = Math.round (Math.random () * 15)
for (i = 1; i < arr1.length; i++)
    arr1[i] = arr1[i - 1] + Math.round (Math.random () * (Math.random () > 0.5 ? 2 : -2))

var arr2 = new Array (120)
arr2[0] = Math.round (Math.random () * 15)
for (i = 1; i < arr2.length; i++)
    arr2[i] = arr2[i - 1] + Math.round (Math.random () * (Math.random () > 0.5 ? 2 : -2))

var arr3 = new Array (120)
arr3[0] = Math.round (Math.random () * 15)
for (i = 1; i < arr3.length; i++)
    arr3[i] = arr3[i - 1] + Math.round (Math.random () * (Math.random () > 0.5 ? 2 : -2))

var arr4 = new Array (120)
arr4[0] = Math.round (Math.random () * 15)
for (i = 1; i < arr4.length; i++)
    arr4[i] = arr4[i - 1] + Math.round (Math.random () * (Math.random () > 0.5 ? 2 : -2))

var config = {
    colors: [
        asciichart.blue,
        asciichart.green,
        asciichart.default, // default color
        undefined, // equivalent to default
    ]
}

console.log (asciichart.plot([ arr1, arr2, arr3, arr4 ], config))