[Chartjs]-In Chart.js set chart title, name of x axis and y axis?

For Chart.js version 3

options = {
  scales: {
    y: {
      title: {
        display: true,
        text: 'Your Title'
      }
    }
  }     
}

For Readers in 2021:

Version

"chart.js": "^3.3.2",

Real World Working Sample:

const optionsTemplate = (yAxisTitle, xAxisTitle) => {
    return {
        scales: {
            yAxes: {
                title: {
                    display: true,
                    text: yAxisTitle,
                    font: {
                        size: 15
                    }
                },
                ticks: {
                    precision: 0
                }
            },
            xAxes: {
                title: {
                    display: true,
                    text: xAxisTitle,
                    font: {
                        size: 15
                    }
                }
            }
        },
        plugins: {
            legend: {
                display: false,
            }
        }
    }
}

If you have already set labels for your axis like how @andyhasit and @Marcus mentioned, and would like to change it at a later time, then you can try this:

chart.options.scales.yAxes[ 0 ].scaleLabel.labelString = "New Label";

Full config for reference:

var chartConfig = {
    type: 'line',
    data: {
      datasets: [ {
        label: 'DefaultLabel',
        backgroundColor: '#ff0000',
        borderColor: '#ff0000',
        fill: false,
        data: [],
      } ]
    },
    options: {
      responsive: true,
      scales: {
        xAxes: [ {
          type: 'time',
          display: true,
          scaleLabel: {
            display: true,
            labelString: 'Date'
          },
          ticks: {
            major: {
              fontStyle: 'bold',
              fontColor: '#FF0000'
            }
          }
        } ],
        yAxes: [ {
          display: true,
          scaleLabel: {
            display: true,
            labelString: 'value'
          }
        } ]
      }
    }
  };

In chart JS 3.5.x, it seems to me the title of axes shall be set as follows (example for x axis, title = ‘seconds’):

options: {
  scales: {x: { title: { display: true, text: 'seconds' }}}
}

see: https://www.chartjs.org/docs/latest/axes/labelling.html

If you are using chart JS v4 try this.

options = {
  scales: {
    y: {
      title: {
        display: true,
        text: 'Test'
      }
    },
    x: {
      title: {
        display: true,
        text: 'Test'
      }
    }
  },
  plugins: {
    legend: {
      display: false,
    },
  }
}

just use this:

<script>
  var ctx = document.getElementById("myChart").getContext('2d');
  var myChart = new Chart(ctx, {
    type: 'bar',
    data: {
      labels: ["1","2","3","4","5","6","7","8","9","10","11",],
      datasets: [{
        label: 'YOUR LABEL',
        backgroundColor: [
          "#566573",
          "#99a3a4",
          "#dc7633",
          "#f5b041",
          "#f7dc6f",
          "#82e0aa",
          "#73c6b6",
          "#5dade2",
          "#a569bd",
          "#ec7063",
          "#a5754a"
        ],
        data: [12, 19, 3, 17, 28, 24, 7, 2,4,14,6],            
      },]
    },
    //HERE COMES THE AXIS Y LABEL
    options : {
      scales: {
        yAxes: [{
          scaleLabel: {
            display: true,
            labelString: 'probability'
          }
        }]
      }
    }
  });
</script>

See example with name of x axis and y axis left and right.

public barChartOptions: ChartOptions = {
    title: {
      display: true,
      text: 'Custom Chart Title',
    },
    responsive: true,
    legend: {
      position: 'right',
    },
    scales: {
      yAxes: [
        {
          position: 'right',
          scaleLabel: {
            display: true,
            labelString: 'Frequency Rate - right',
          },
        },
        {
          position: 'left',
          scaleLabel: {
            display: true,
            labelString: 'Frequency Rate - left',
          },
        },
      ],
      xAxes: [
        {
          display: true,
          position: 'bottom',
          scaleLabel: {
            display: true,
            labelString: 'Titulo do eixo X',
            fontStyle: 'italic',
            fontSize: 12,
            fontColor: '#030',
          },
        },
      ],
    },
  };

To name the axis:

1. inside new Chart()
2. Go to options (or create it):

options: {

    scales: {
      x: {
        title: { display: true, text: 'X axis label' }
      },
      y: {
        title: { display: true, text: 'Y axis label'}
      }
    },   }

Remember: new Chart() -> options -> scales -> x or y -> title

          <Scatter
            data={data}
            // style={{ width: "50%", height: "50%" }}
            options={{
              scales: {
                yAxes: [
                  {
                    scaleLabel: {
                      display: true,
                      labelString: "Probability",
                    },
                  },
                ],
                xAxes: [
                  {
                    scaleLabel: {
                      display: true,
                      labelString: "Hours",
                    },
                  },
                ],
              },
            }}
          />