once
Run a function exactly one time
once
Only call a function once.
usage
var once = { cb = loader loader loader}
Or add to the Function.prototype in a responsible way:
// only has to be done once { cb = cb loader loader loader}
Ironically, the prototype feature makes this module twice as complicated as necessary.
To check whether you function has been called, use fn.called
. Once the
function is called for the first time the return value of the original
function is saved in fn.value
and subsequent calls will continue to
return this value.
var once = { cb = var stream = stream stream}
once.strict(func)
Throw an error if the function is called twice.
Some functions are expected to be called only once. Using once
for them would
potentially hide logical errors.
In the example below, the greet
function has to call the callback only once:
{ // return is missing from the if statement // when no name is passed, the callback is called twice if !name } { console} // this will print 'Hello anonymous' but the logical error will be missed // once.strict will print 'Hello anonymous' and throw an error when the callback will be called the second time