javascript - 异步 - 传递变量并保留上下文

Question

如果您有以下代码：

var asyncConfig = {};
var a, b;
for(var i = 0; i < someValue; i++) {
    // do something with a
    // do something with b
    asyncConfig[i] = function(callback) {
        func(a, b, callback); // func is async
    }
}
// Include some more parallel or series functions to asyncConfig
async.auto(asyncConfig);

• 如何传递变量的值a和bto func以便在循环async.auto(asyncConfig)之后执行时，保留and的上下文？forab

（每次执行的a不同上下文。）bfunc

先感谢您 ！

Answer 1

var asyncConfig = {};
var a, b;
for(var i = 0; i < someValue; i++) {
    // do something with a
    // do something with b
    (function(a,b){
      asyncConfig[i] = function(callback) {
        func(a, b, callback); // func is async
      }
    })(a,b);
}
// Include some more parallel or series functions to asyncConfig
async.auto(asyncConfig);

Answer 2

使用bind的可能替代方法：

var asyncConfig = {};
var a, b;
for(var i = 0; i < someValue; i++) {
    // do something with a
    // do something with b
    asyncConfig[i] = func.bind(asyncConfig, a, b);
}
// Include some more parallel or series functions to asyncConfig
async.auto(asyncConfig);

确保检查您使用此支持的环境是否绑定。此外，我将“this”值绑定到asyncConfig，这可能不适合您。

编辑：再次阅读问题，是 a 和 b 原语还是对象/数组？如果它们不是原语，那么您将需要克隆它们。