Chartjs-How i can insert string data to diagrams in chart.js

The code that you show us seems right, the only thing that you need is to shift the data in the dataset before adding the new value, like:

socket.on('temp', function(data) { 
    console.log(data.temp);
    document.getElementById('date').innerHTML = data.date; 
    chart.data.datasets.forEach((dataset) => {
        dataset.data.shift();
        dataset.data.push(data.temp); 
    });
    chart.update();
});