called function A(args) calls a function B() which then calls a function A(args), How to do that?
See example:
<!DOCTYPE html>
<html>
<head>
<title>language</title>
<script type="text/javascript" src="http://www.google.com/jsapi">
</script>
</head>
<body>
<div id="language"></div>
<script type="text/javascript">
var loaded = false;
function load_api() {
google.load("language", "1开发者_JAVA百科", {
"nocss": true,
"callback": function() {
loaded = true;
callback_to_caller(with_caller_agruments);
// how to call a function (with the same arguments) which called load_api() ???
// case 1 should be: detect_language('testing');
// case 2 should be: translate('some text');
}
});
}
function detect_language(text) {
if (!loaded) {
load_api();
} else {
// let's continue... believe that google.language is loaded & ready to use
google.language.detect(text, function(result) {
if (!result.error && result.language) {
document.getElementById('language').innerHTML = result.language;
}
});
}
}
function translate(text) {
if (!loaded) {
load_api();
} else {
// let's continue...
}
}
detect_language('testing'); // case 1
translate('some text'); // case 2
</script>
</body>
</html>
You need to pass the caller and arguments to load_api, otherwise how could it know the values of the irrelevant variables?
function load_api(f, text) {
...
function detect_language(text) {
if (!loaded) {
load_api(detect_language, text); // or use load_api(arguments.callee, text)
And then you can invoke those in the callback.
"callback": function() {
loaded = true;
f(text);
If A is variadic, you can use the arguments variable and Function.apply:
function A (x, y, z) {
B(A, arguments); // or B(A, [x, y, z])
}
function B (f, arr) {
setTimeout(1000, function() {
f.apply(this, arr);
});
}
If you call google.load more than once, it is smart enough not to include the script again, but your callback will still get called. Thus, you can just do:
function load_api(callback) {
google.load("language", "1", {
"nocss": true,
"callback": callback
});
}
function detect_language(text) {
load_api(function() {
// let's continue... believe that google.language is loaded & ready to use
google.language.detect(text, function(result) {
if (!result.error && result.language) {
document.getElementById('language').innerHTML = result.language;
}
});
});
}
function translate(text) {
load_api(function()
{
// Do whatever you want, including using text.
});
}
Note that because of the way closures work, you can freely use the function arguments in your callback. But you may find it simpler to just have a single callback at page load, and hide any translation controls until the callback completes.
加载中,请稍侯......
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