Javascript programming functions

Question

If i have a function that receives a call like

function car_total(y) {

final_total(y);
}


function toy_total(x) {

final_total(x);
}

How can I make a function that computes both totals if they exist but can only receive 1 parameter and not throw an error, is this possible?

function final_total(x,y) {
//if passed just x
sum = x ;
//if passed just y 
sum = y;
//if passed x, y 
sum = x + y ; 

}

this should help you out, it's a previous post: http://stackoverflow.com/questions/2141520/javascript-variable-number-of-arguments-to-function — Jay Blanchard, Nov 21 '12 at 20:05

David Thomas · Answer 1 · 2012-11-21T20:13:25.043

You can pass only one argument, but with only one argument that argument must be x; as there's no way (without passing an object) of determining which variable you 'meant' to pass in. Therefore the first variable recieved will always be x, the second y, that said, though, I'd suggest:

function final_total(x,y) {
    return y ? x + y : x;
}

And, in the presence of only one passed-in argument this function returns that single value or, given two variables, returns the sum of those two. So this does do as you want, even if there's no way to ascertain whether x or y was passed-in.

If, however, you must explicitly pass in either x or y (for some reason):

function final_total(values) {
    var x = values.x || 0,
        y = values.y || 0;
    return x + y;
}

var variableName1 = final_total({x : 23, y : 4});
console.log(variableName1);
// 27

var variableName2 = final_total({y : 4});
console.log(variableName2);
// 4

var variableName3 = final_total({x : 23});
console.log(variableName3);
// 23

JS Fiddle demo.

score 0 · Answer 2 · answered Nov 21 '12 at 20:06

0

You could define the function like you have it, and then check if either of the arguments are null. The downside is you would have to make sure to put the null in the right place when you call it.

function final_total(x,y) {

    if(x && y) sum = x + y;
    else if (x) sum = x;
    else if (y) sum = y; 

}

answered Nov 21 '12 at 20:06

WildCrustacean

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`x` will be undefined, and anyway this is the most possible verbose way. – gdoron is supporting Monica Nov 21 '12 at 20:08
What do you mean `x` will be undefined? Unless it gets called with no arguments, `x` should have something. I know this is the most verbose way, but I figured I'd post it anyway. Sometimes verbose is good at first. – WildCrustacean Nov 21 '12 at 20:51
[I mean this](http://jsfiddle.net/HMa7C/) `x` gives you the value `undefined` which `== null` but doesn't `=== null` by the way. – gdoron is supporting Monica Nov 21 '12 at 22:08
Ok, that makes sense. I like your answer better anyway. – WildCrustacean Nov 21 '12 at 22:12

score 0 · Answer 3 · answered Nov 21 '12 at 20:14

0

var final_total = function(x,y) { return x+(y||0); };

answered Nov 21 '12 at 20:14

neiker

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Returns `NaN` when no arguments are provided, not sure if the OP is concerned about the output in this case. – Asad Saeeduddin Nov 21 '12 at 20:15
She asked to use it with 1 parameter.. if you want thats works without arguments use: var final_total = function(x,y) { return (x||0)+(y||0); }; – neiker Nov 21 '12 at 20:34

Javascript programming functions

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