javascript 如何将更改事件处理程序附加到变量？
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How can I attach a change event handler to a variable?
提问by Travis J
Possible Duplicate:
Listening for variable changes in JavaScript or jQuery
How can I track if this variable has changed?
如何跟踪此变量是否已更改？
var ConditionalFlag = 0;
I tried this:
我试过这个：
var ConditionalFlag = 0;
$(ConditionalFlag).change(function () {
alert("Changed");
});
ConditionalFlag++;
But to no avail. I have considered using a 25ms timer to check for change like this:
但无济于事。我曾考虑使用 25ms 计时器来检查这样的变化：
var ConditionalFlag = 0;
function CheckFlag() {
if (ConditionalFlag > 0) {
alert("Changed");
clearInterval(check);
}
}
var check = window.setInterval("CheckFlag()", 25);
ConditionalFlag++;
However, that seems like overkill. Is there a way to attach an event handler to this variable with jQuery or javascript?
然而，这似乎有点矫枉过正。有没有办法使用 jQuery 或 javascript 将事件处理程序附加到这个变量？
采纳答案by Rocket Hazmat
There's no "event" that gets triggered when a variable changes. JavaScript doesn't work that way.
当变量发生变化时，不会触发“事件”。JavaScript 不是这样工作的。
When does this variable get changed? Just add a call to a function after it does.
这个变量什么时候改变？只需在调用后添加对函数的调用。
回答by Travis J
If it's a global variable, you can use property accessors in supported environments...
如果它是全局变量，则可以在支持的环境中使用属性访问器...
window._conditional_flag = 0;
Object.defineProperty(window, "ConditionalFlag", {
get: function() { return window._conditional_flag},
set: function(v) { console.log("changed"); window._conditional_flag = v; }
});
