在块 [] 中使用 if-else 语句

Question

I have the following statement:

arr.push([student.name,student.id]);

I want to add an if-else block in this statement so I could add student.name only if the if is true, something like:

arr.push([student.name if (validName(student.name))
         ,student.id]);

But this syntax is not valid. Is there a proper way to achieve this idea?

EDIT :

My array contains a lot of elements and I want to add to most of them (if not all of them) some kind of check. Something like:

    arr.push([student.name if (validName(student.name)),
              student.id   if (validId(student.id) && idContainsNine(student.id)),
              student.avg  if (student.avg !== 'undefined'),
              ...
              ]);

I push the values only if the if statement is true. If it false, it will not push it. for example if validName(student.name) returns false it will not push student.name in the array.

Answer 1

You could take a conditional operator and get only an array with valid values.

array.push(validName(student.name)
    ? [student.name, student.id]
    : [student.id]
);

---

An other approach is to use functions which return after a check either an array with the value or without.

For using this result, you need to spread the array and if it does not contain any element, it does not increase the length of the array.

cost 
    includeName = name => validName(name) ? [name] : [],
    includeId = id => validId(id) && idContainsNine(id) ? [id] : [],
    includeAVG = avg => avg !== 'undefined' ? [avg] : [];

arr.push([
    ...includeName(student.name),
    ...includeId(student.id),
    ...includeAVG(student.avg)
]);

---

Another solution could be to use an array of checks and return in case of unwanted items an own Symbol (if undefined or ``null` is a used value) and filter the array before pushing it to the result set.

const
    EMPTY = new Symbol('empty'),
    checkName = ({ name }) => validName(name) ? name : EMPTY,
    checkId = ({ id }) => validId(id) && idContainsNine(id) ? id : EMPTY,
    checkAVG = ({ avg }) => avg !== 'undefined' ? avg : EMPTY;


array.push([checkName, checkId, checkAVG]
    .map(fn => fn(student))
    .filter(v => v !== EMPTY)
);

Answer 2

Consider ternary operator.

arr.push([validName(student.name) ? student.name : '', student.id]);

Replace empty string value '' with what you want when you get invalid student.name .

Answer 3

Use this one.It may help you.

arr.push([student.name,(student.id ? student.id : '')]);

Answer 4

you can use && operator, second statement will be executed only if the first one is true.

  validName(student.name) && arr.push([student.name,student.id]);