In the following code, the function findById()
does not actually return anything. The console.log()
s fire and print as expected but the result is that the variable the function is being called to is undefined.
I have tried to change return value types, even simply putting return true;
at the end with no conditional, but it always is undefined. To make sure I was not missing something simple I actually created a function that only returns a value istrue()
. This actually works fine.
This is the object/method def
const database = {
// List of authenticated characters
characters: [],
addCharacter: function(c) {
this.characters.push(c);
},
findById: function(id) {
console.log('Searching for character...');
this.characters.forEach((c) => {
if (c.id === id) {
console.log('Found');
console.log('cid: ' + c.id);
console.log('id: ' + id);
return true; // Never actually returns
}
});
},
istrue: function() {
return true;
}
};
and where it is being called
const find = database.findById(characterIdToFind);
console.log(typeof find); // always undefined
console.log(find); // always undefined
I expect there to be some kind of return value in at least one of the permutations of this function I have tried. There is never any change in the return value of the function, simply undefined
.
The return
statement inside a nested function return from function.
In this case you could use some()
instead of forEach()
because you can't break forEach
.
findById: function(id) {
console.log('Searching for character...');
return this.characters.some(c => c.id === id)
}
If you want to get the object which matches the given condition that use find()
findById: function(id) {
console.log('Searching for character...');
return this.characters.find(c => c.id === id)
}
If you see in above both method we are returning c.id === id
implicitly in each iteration but it doesn't return
from outer function.
这是因为您尝试从forEach
返回并且forEach
不返回任何内容
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