Omit/Skip a parameter with default value while calling a function in JS

Question

In python we can omit a parameter with its default value in a function call. e.g.

def post(url, params={}, body={}):
    print()
    print(url)
    print(params)
    print(body)

post("http://localhost/users")

post("http://localhost/users", {"firstname": "John", "lastname": "Doe"})           # Skipped last argument (possible in JS as well)
post("http://localhost/users", params={"firstname": "John", "lastname": "Doe"})    # same as above

post("http://localhost", body={"email": "[email protected]", "password": "secret"})   # Skipped 2nd argument by passing last one with name (i.e. "body")

Can I achieve this in JS? Like omitting the 2nd argument and just pass the last one. (As in the last case). Other cases are possible in JS but I can't find a way to achieve the last one

Possible duplicate of [Skip arguments in a JavaScript function ](stackoverflow.com/questions/32518615/…) — rassar
– rassar, Commented Oct 30, 2019 at 14:05

Hossein Alipour · Accepted Answer · 2019-10-30 14:07:24Z

4

You can achieve that by object destructions:

function post({ param1, param2 = "optional default value", param3 , param4}){
 /// definitions
}

let param3 = 'abc';
post({param1: 'abc', param3})

answered Oct 30, 2019 at 14:07

Hossein Alipour

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jstuartmilne · Accepted Answer · 2019-10-30 14:11:55Z

3

You cant ommit a parameter and call it by its name. Omitting in js would mean to pass undefined so if your post was a 3 argument function you would do

post('http://whatever', undefined,'somebody')

So that the second param takes the default value

However what you can do is take an object as the parameter, destructure and assign default values:

function post({url,params={},body={}}){
}

Then to call the function you would do post({url:'http://whatever',body:'somebody'});

edited Oct 30, 2019 at 14:11

answered Oct 30, 2019 at 14:05

jstuartmilne

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1 Comment

TalESid Over a year ago

So the query is not directly supported in JS! But this is the nice alternative solution... Thanks

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