I saw this function:
(function (x, y, data, lbl, dot) {
// Function body...
})(x, y, data[i], labels[i], dot);
What is this? A function? Why place a function definition in ()
?
问题
I saw this function:
(function (x, y, data, lbl, dot) {
// Function body...
})(x, y, data[i], labels[i], dot);
What is this? A function? Why place a function definition in ()
?
回答1
In javascript you can have anonymous
and self invoking
functions.
function add(a, b)
{
return a + b;
}
is same as
var add = function (a, b) {
return a + b;
}
and you call these as
add(10, 20)
You can define the function and call it immediately as
(
function(a, b)
{
return a + b;
}
)(10, 20);
The
(
function(a, b)
{
return a + b;
}
)
part defines a function, and the (10, 20)
immediately after it calls the function just defined, with 10 and 20 as arguments to it.
Since the function does not have a name, it cannot be used later in the code.
The code in your question is probably minified, and creates a function in a similar way and calls it immediately.