Javascript skipping arguments in function call
javascript beginner here.
Let's say I have a javascript function that takes 3 arguments:
function f(arg1, arg2, arg3) { // do stuff }
I know I can call f (value1, value2); and in this case, inside the function scope, arg1 would be value1, arg2 would be value2, and arg3 would be null.
Everything is good. However, if I want to call a function that gives values only arg1
and arg3
, I need to do something like this f(value1, null, value2)
:;
Is there a way to specify which arguments should have which values in a more C #-esque manner (without specifying unspecified arguments as null)? Something like this: to call f with values only for arg1
and arg3
I would writef(value1, arg3 = value2);
Any ideas? Hooray!
there is a way i saw for this:
eg
function person(name,surname,age)
{
...
}
person('Xavier',null,30);
You can do it:
function person(paramObj)
{
var name = paramObj.name;
var surname = paramObj.surname;
var age = paramObj.age;
}
calls the following:
person({name:'Xavier',age:30});
I think this is the closest that you will be able to do this, as in C # keep in mind that JS does not compile, so you cannot predict the function arguments.
The only way you could do it with JS is to pass one array containing all the parameters.
The default values must be set inside the function - you cannot define default values for arguments in JavaScript.
function foo( args ){
var arg1 = args[ 0 ] || "default_value";
var arg2 = args[ 1 ] || 0;
///etc...
}
Better yet, instead of an array, you can pass a simple object that will allow you to access the arguments by their key in the object:
function foo( params ){
var arg1 = params[ "arg1" ] || "default_value";
var arg2 = params[ "arg2" ] || 0;
///etc...
}
If you are going to do (say it really is)
f(value1, arg3 = value2)
Then argument 2 will be undefined, so just pass this:
f(value1, undefined, value2)
Yes, you can. It can be written as:
function f(arg1, undefined, arg3) { // do stuff }
Arguments 1 and 3 are passed in this call, and argument 2 will not be sent.
Add this code to your function (for default values)
function f(a, b, c)
{
a = typeof a !== 'undefined' ? a : 42;
b = typeof b !== 'undefined' ? b : 'default_b';
a = typeof c !== 'undefined' ? c : 43;
}
call a function like this
f(arg1 , undefined, arg3)