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我一直在关闭闭包中的这篇文章:Understand Javascript Closures with Ease封闭内循环,内部IIFE是什么?
最后一个例子处理了for循环中的闭包。
我明白为什么使用IIFE将'i'的当前值捕获为'j'。我不明白这个例子是为什么有一个第二,内部IIFE包裹在返回语句。 (我的评论在下面的代码中有上限)。
该代码似乎没有内部IIFE工作。 See CodePen here.
由于某种原因,这个内部函数是必需的,还是这只是作者的疏忽?
function celebrityIDCreator (theCelebrities) {
var i;
var uniqueID = 100;
for (i = 0; i < theCelebrities.length; i++) {
theCelebrities[i]["id"] = function (j) { // the j parametric variable is the i passed in on invocation of this IIFE
return function() { //<--WHY DOES THIS INNER FUNCTION NEED TO BE HERE?
return uniqueID + j; // each iteration of the for loop passes the current value of i into this IIFE and it saves the correct value to the array
}() // BY adding() at the end of this function, we are executing it immediately and returning just the value of uniqueID + j, instead of returning a function.
} (i); // immediately invoke the function passing the i variable as a parameter
}
return theCelebrities;
}
var actionCelebs = [{name:"Stallone", id:0}, {name:"Cruise", id:0},{name:"Willis", id:0}];
var createIdForActionCelebs = celebrityIDCreator (actionCelebs);
var stalloneID = createIdForActionCelebs [0];
console.log(stalloneID.id); // 100
var cruiseID = createIdForActionCelebs [1];
console.log(cruiseID.id); // 101
var willisID = createIdForActionCelebs[2];
console.log(willisID.id); //102