Passing the argument name while calling function in javascript

Question

I have a function which looks like this:

function helo(a,b){
    if(a)
    {
       //do something
    }
    if(b)
    {
       //do something
    }
}

Now if I want to specify which parameter has to be passed while calling helo, how do I do it in javascript, ie

If I want to send only parameter b, how do I call the function helo?

helo(parameterB); 

Right now parameter a takes the value

Answer 1

Your best bet would be to just pass an object containing all parameters:

function myFunction(parameters){
    if(parameters.a) {
        //do something
    }
    if(parameters.b) {
        //do something
    }
}

Then you can call the function like this:

myFunction({b: someValue}); // Nah, I don't want to pass `a`, only `b`.

In case you want to be able to pass falsy values as parameters, you're going have to change the if sa bit:

if(parameters && parameters.hasOwnProperty('a')){
    //do something
}

---

Another option would be to simply pass null (or any other falsy value) for parameters you don't want to use:

helo(null, parameterB); 

Answer 2

在JavaScript中，参数根据顺序进行匹配，因此如果您只想传递第二个参数，则必须先将第一个参数保留为空

helo(null,parameterB); 

Answer 3

Instead of passing multiple distinct arguments, you can pass in a single argument, which is an object.

For Example:

function helo(args){
    if(args.a){ ... }
    if(args.b){ ... }
}

helo({b: 'value'});

Answer 4

You can use either of the below two syntax:

helo(null,parameterB); 

or

helo(undefined,parameterB);