javascript - 立即将函数返回给函数有什么好处？

Question

我指的是它将函数 findMatches 返回到 substringMatcher 的位置。substringMatcher 现在接受一个或两个参数吗？

var substringMatcher = function(strs) {
    return function findMatches(q, cb) {
    var matches, substringRegex;

    // an array that will be populated with substring matches
    matches = ["Your Location"];

    // regex used to determine if a string contains the substring `q`
    substrRegex = new RegExp(q, 'i');

    // iterate through the pool of strings and for any string that
    // contains the substring `q`, add it to the `matches` array
    $.each(strs, function(i, str) {
            if (substrRegex.test(str)) {
                matches.push(str);
            }
        });

        cb(matches);
        };
};

Answer 1

这是一个闭包。为了解释，我强烈建议通过 this .我自己无法更好地解释它。我只会从那里引用:

Simply accessing variables outside of your immediate lexical scope creates a closure.

要调用您的函数，您可以编写 substringMatcher(strs)(q, cb); 所以答案是 substringMatcher 接受一个参数并返回一个接受两个参数的函数。你也可以这样写:

var findMatches = substringMatcher(strs);
var result = findMatches(q, cb);