Question

在以下代码中，（玩具）函数f1和f2来自库，因此我无法更改它们。

function f1() { // cannot change this
   var x;
   alert(x.y); // throws an error because x is undefined
}
function f2() { // cannot change this either
   setTimeout(f1, 1000); // creates an asynchronous timeout
}

现在我想抓住错误：

try { // does not work because of the asynchronous environment
   f2();
} catch (error) {
   console.log('caught: ' + error);
}

但我知道这不起作用，因为setTimeout创建的环境不是指定try-catch块的环境。

还有其他可能性来捕获错误吗？

Answer 1

您可以通过覆盖f1功能...

来完成此操作

＆＃13;

// original functions -- this is all the code you can't modify
function f1() {
  throw "Oh no - an exception!";
}

function f2() {
  try {
    setTimeout(f1, 1000);
  }
  catch(e) {
    alert(e + " - this is handled in the original code");
  }
}
// end of the code you can't modify



// keep a reference to the original f1 function
var __f1 = f1;

// override the original f1 function
var f1 = function() {
  try {
    // this calls the original version of f1(), along with any parameters
    return __f1.apply(this, arguments);
  }
  catch(e) {
    alert(e + " - this is handled in your new code");
  }
};

// execute...
f2();

＆＃13;

给定异步函数的错误处理（try-catch）

1 个答案: