var name2 = ''; setTimeout(function(){ var mode = document.getElementById("mode").textContent; console.log(mode); if(mode === 'Slave_P1'){ name2 = 'P1 Oneway Time(ps)'; }else if(mode === 'Slave_P2'){ name2 = 'P2 Oneway Time(ps)'; } var ctx4 = document.getElementById('myChart4').getContext('2d'); var chart4 = new Chart(ctx4, { type: 'line', data: { labels: [], // 时间数组，初始为空 datasets: [{ label: name2, data: [], // 数据数组，初始为空 backgroundColor: 'rgba(255, 99, 132, 0.2)', borderColor: 'rgba(255, 99, 132, 1)', borderWidth: 1 }] }, options: { scales: { xAxes: [{ type: 'time', time: { displayFormats: { second: 'h:mm:ss' // 时间格式 } }, ticks: { autoSkip: true, maxTicksLimit: 20 // 最多显示50个标签 } }] } } }); },15000); 通过回调函数将name2的值传递到函数外部

可以将name2的值作为参数传递给回调函数，然后在回调函数中调用函数外部定义的函数并将name2作为参数传递给它。例如：

var name2 = '';

setTimeout(function(name2) {
  var mode = document.getElementById("mode").textContent;
  console.log(mode);
  
  if (mode === 'Slave_P1') {
    name2 = 'P1 Oneway Time(ps)';
  } else if (mode === 'Slave_P2') {
    name2 = 'P2 Oneway Time(ps)';
  }
  
  var ctx4 = document.getElementById('myChart4').getContext('2d');
  var chart4 = new Chart(ctx4, {
    type: 'line',
    data: {
      labels: [],
      datasets: [{
        label: name2,
        data: [],
        backgroundColor: 'rgba(255, 99, 132, 0.2)',
        borderColor: 'rgba(255, 99, 132, 1)',
        borderWidth: 1
      }]
    },
    options: {
      scales: {
        xAxes: [{
          type: 'time',
          time: {
            displayFormats: {
              second: 'h:mm:ss'
            }
          },
          ticks: {
            autoSkip: true,
            maxTicksLimit: 20
          }
        }]
      }
    }
  });
  
  // Call a function defined outside the callback and pass name2 as a parameter
  myFunction(name2);
  
}, 15000, name2);

function myFunction(name) {
  console.log('name2 value outside callback: ' + name);
}

这样，在回调函数中就可以通过参数访问到name2的值，并将其传递给函数外部的函数。