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将某些JavaScript转换为CoffeeScript时遇到了问题。基本问题是,我从使用$ .each去了CoffeeScript的解释,现在我有一个问题,在关闭中捕获最后一个理解值。让我们开始与原来的JavaScript:Coffeescript解析和关闭问题
function bindKeyboardControls(websocket) {
var moveKeyMap = {
Down: ['down', 's'],
Up: ['up', 'w'],
Left: ['left', 'a'],
Right: ['right', 'd']
};
$.each(moveKeyMap, function (direction, keys) {
$.each(keys, function (_, key) {
$(document).bind('keydown', key, function() { move(websocket, direction); });
});
});
};
这是我与CoffeeScript的第一次尝试:
bindKeyboardControls = (websocket) ->
moveKeyMap =
Down: ['down', 's']
Up: ['up', 'w']
Left: ['left', 'a']
Right: ['right', 'd']
for direction, keys of moveKeyMap
for key in keys
$(document).bind('keydown', key, -> move(websocket, direction))
null
为什么不工作的呢?那么这里生成的JavaScript:
bindKeyboardControls = function(websocket) {
var direction, key, keys, moveKeyMap, _i, _len;
moveKeyMap = {
Down: ['down', 's'],
Up: ['up', 'w'],
Left: ['left', 'a'],
Right: ['right', 'd']
};
for (direction in moveKeyMap) {
keys = moveKeyMap[direction];
for (_i = 0, _len = keys.length; _i < _len; _i++) {
key = keys[_i];
$(document).bind('keydown', key, function() {
return move(websocket, direction);
});
}
}
return null;
};
您是否看到'direction'变量是如何在函数顶部声明的?传递给document.bind的函数是在该变量上创建一个闭包,所以在函数运行时,方向将始终等于最后一个值('Right')。
这里是一个固定的版本,有点丑:
bindKeyboardControls = (websocket) ->
moveKeyMap =
Down: ['down', 's']
Up: ['up', 'w']
Left: ['left', 'a']
Right: ['right', 'd']
for direction, keys of moveKeyMap
for key in keys
((d) -> $(document).bind('keydown', key, -> move(websocket, d)))(direction)
null
我也只是回到使用$。每。所以我确实有一些解决方案,但是有更好的解决方案吗?
'做'正是我所需要的。谢谢! –