Line charts are one of the most effective ways to visualize data that changes over time. In dashboards, you commonly use line charts to display trends, such as website traffic across days, monthly sales, or temperature readings throughout a week. Their strength lies in making it easy to spot patterns, peaks, and valleys in sequential data, helping you quickly identify growth, declines, or anomalies.

To create a line chart in Chart.js within a React application, you need to provide data in a specific structure. Chart.js expects an object with two main properties: labels and datasets. The labels array contains the values that appear along the x-axis—typically time intervals such as days, months, or years. The datasets array contains one or more objects, each representing a line on the chart. Each dataset object includes at least a label (the name of the dataset), a data array (the y-axis values for each label), and usually a borderColor to distinguish the line visually.

For example, if you want to show daily active users over a week, your data object might look like this:

const data = {
  labels: ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"],
  datasets: [
    {
      label: "Active Users",
      data: [120, 200, 150, 170, 180, 210, 240],
      borderColor: "rgba(75,192,192,1)",
      tension: 0.4
    }
  ]
};

Configuring axes, labels, and datasets is essential for a clear and informative line chart. The labels property determines what appears on the x-axis, so choose values that best represent your time intervals or categories. Each dataset in the datasets array can have its own styling and label, allowing you to compare multiple trends on the same chart. For the y-axis, Chart.js automatically scales based on your data values, but you can further customize the axes using options such as beginAtZero, min, max, or by adding axis titles for clarity.

To summarize, building a line chart involves defining your labels for the x-axis, creating one or more datasets with corresponding data points, and configuring chart options to fine-tune the appearance and behavior of your axes and labels. This structure makes it straightforward to present time-based trends in your React dashboard using Chart.js.