for example we have 3 params
function test(a,b,c){
console.log(a + ',' + b + ',' + c +'.')
}
test('a','b','c')
will print
> a, b, c.
but in case b will be empty, the result will look with two comma, like
test('a','','c')
will print
a,,c.
we can improve like checking each var like this
function test(a,b,c){
console.log(a + (a?',':'') + b + (b?',':'') + c +(c?'.':''))
}
so now
test('a','','c')
will print
a,c.
look ok, but when we have only b
test('','b','')
will print
b,
and now we must to check values a or b exist and there is no c to print '.'
and complexity increases, but what if we have n vars, any ideas how to solve more easily
expected result is :
test('a','b','c') => a, b, c.
test('a','b','') => a, b.
test('a','','') => a.
test('','b','c') => b, c.
test('','b','') => b.
test('','','') =>
You can filter and use the ...rest parameter
const isParm = prm => prm !== "" && prm !== undefined && prm !== null;
const test = (...theArgs) => {
const list = theArgs.filter(parm => isParm(parm));
if (list.length > 0) console.log(`${list.join(",")}.`)
}
let x;
test('a','b','c')
test('a',null,'c'); // null is a falsy value
test('','','c')
test('a')
test('','b')
test(x); // undefined (falsy)
test(0,0,0); // falsy valuesIf I understand your intention, this should do it.
function test(...args) {
const res = args.filter(i => i).join(',')
return res + (res && ".")
}
// Usage
console.log(test('a','','c')); // "a,c."
console.log(test('a','b','c')); // "a,b,c."
console.log(test('','','c')); // "c."
console.log(test('a', '', '')) // "a."
console.log(test('', '', '')) // ""Using an array join approach, we can add all inputs to an array. Then filter off empty entries and join by a comma separator.
function test(a,b,c) {
var array = [a, b, c];
return array.filter(x => x).join(", ") + ".";
}
console.log(test('a','','c'));Actually, a better function signature for your function would accept an array, which allows for concat with separator of any number of items.