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);

如何将变量a和b的值传递给func，以便在async.auto(asyncConfig)循环后执行for时，上下文保留a和b？

（每次执行a时b和func的上下文不同。）

提前谢谢！

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的可能替代方案：

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);

确保检查使用此支持的环境是否绑定。另外，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基元还是对象/数组？如果它们不是原语，那么你就想要克隆它们。

异步 - 传递变量和保留上下文

2 个答案: