点击即可杀死所有正在运行的JavaScript函数

时间:2018-05-03 02:57:32

标签: javascript function

这是我之前提问的延伸,主要是出于好奇:Kill all running JavaScript functions with Timeouts on click

我有一个包含3个按钮和“结果”部分的网页:

<button id="b1" onclick="f1()">1st button</button>
<button id="b2" onclick="f2()">2nd button</button>
<button id="b3" onclick="f3()">3rd button</button>
<p id="result">"Here will be the result!"</p>

以下是JavaScript函数的代码段。我还利用了网络工作者:

// The functions are similar, but the outputs are different

var worker;

function calcF1() {
    var answer;
    for (let i = 0; i < 1e9; i++) {
        // Do some complicated calculations
    }
    postMessage(answer);
}

function f1() {
    // TODO: Kill other running instances of all functions

    // Calling worker
    var cf1 = calcF1.toString();
    var code = cf1.substring(cf1.indexOf('{')+1, cf1.lastIndexOf('}'));
    var blob = new Blob([code], {type: 'application/javascript'});
    worker = new Worker(URL.createObjectURL(blob));

    worker.onmessage = message => {
        document.getElementById("result").innerHTML = "1st function";
    };
}

function calcF2() {
    var answer;
    for (let i = 0; i < 1e9; i++) {
        // Do some complicated calculations
    }
    postMessage(answer);
}

function f2() {
    // TODO: Kill other running instances of all functions

    // Calling worker
    var cf2 = calcF2.toString();
    var code = cf2.substring(cf2.indexOf('{')+1, cf2.lastIndexOf('}'));
    var blob = new Blob([code], {type: 'application/javascript'});
    worker = new Worker(URL.createObjectURL(blob));

    worker.onmessage = message => {
        document.getElementById("result").innerHTML = "2nd function";
    };
}

function calcF3() {
    var answer;
    for (let i = 0; i < 1e9; i++) {
        // Do some complicated calculations
    }
    postMessage(answer);
}

function f3() {
    // TODO: Kill other running instances of all functions

    // Calling worker
    var cf3 = calcF3.toString();
    var code = cf3.substring(cf3.indexOf('{')+1, cf3.lastIndexOf('}'));
    var blob = new Blob([code], {type: 'application/javascript'});
    worker = new Worker(URL.createObjectURL(blob));

    worker.onmessage = message => {
        document.getElementById("result").innerHTML = "3rd function";
    };
}

但是,如果用户点击b1然后立即点击b2,则f1旁边的工作人员将不会终止并继续运行。如果来自f1的工作人员在f2之前完成,则result将显示1st function,然后由2nd function替换。 f2之前的工作人员也可能先完成,在这种情况下result会显示2nd function,然后由1st function替换。

我想要的是在每个函数的开头实现一个语句,该语句杀死/忽略/绕过当前正在运行的所有函数和/或所有Web工作者,以便最终输出始终是与用户按下的最后一个按钮。如何才能最好地实施?

编辑:感谢您指出网络工作者。我最初的实现涉及网络工作者,但我忘了提及。问题已经更新。

1 个答案:

答案 0 :(得分:1)

拆分这些函数,使它们只运行一段时间,然后停止并使用setTimeout将下一次运行推送到堆栈的末尾,以便其他函数有机会运行。在每个f1f2f3的开头,检查他们是否具有对当前运行功能的键的唯一引用,如果他们不在,则返回。吨。

在以下代码段中,正在进行的f1功能被最近一次f2的调用覆盖:

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let runningFunctionKey;
function f1(key, start = 0) {
  if (!key) {
    runningFunctionKey = {}; // some unique reference
    key = runningFunctionKey;
  } else if (key !== runningFunctionKey) return;
  const until = start + 1e7;
  while (start < until) {
    if (start === 1e9) {
      console.log('f1 done');
      return;
    }
    start++;
  }
  console.log('f1 setting timeout');
  setTimeout(f1, 0, key, start);
}
function f2(key, start = 0) {
  if (!key) {
    runningFunctionKey = {}; // some unique reference
    key = runningFunctionKey;
  } else if (key !== runningFunctionKey) return;
  const until = start + 1e7;
  while (start < until) {
    if (start === 1e9) {
      console.log('f2 done');
      return;
    }
    start++;
  }
  console.log('f2 setting timeout');
  setTimeout(f2, 0, key, start);
}
f1();
setTimeout(f2, 500);
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