I want to know how to write,if(foo === 'apple' && bar === 'apple'){then do something} without having to repeat the word apple. So if I am checking many conditions are equal to something. I would write this something if(foo && bar === 'apple') but that just checks if foo exists and bar === 'apple'. Is there a way to do this?
Basically reduce the necessity to repeat the word apple.
You can use Array#every to verify all your conditions:
let foo = "apple";
let bar = "apple";
let baz = "banana";
if ([foo, bar].every(x => x === "apple")) {
console.log("foo and bar are apple");
} else {
console.log("foo and bar are NOT apple");
}
if ([foo, bar, baz].every(x => x === "apple")) {
console.log("foo, bar, and baz are apple");
} else {
console.log("foo, bar, and baz are NOT apple");
}You can extract this check to a small helper function to make things easier, too:
let foo = "apple";
let bar = "apple";
let baz = "banana";
const is = target => x => x === value;
if ([foo, bar].every(is("apple"))) {
console.log("foo and bar are apple");
} else {
console.log("foo and bar are NOT apple");
}
if ([foo, bar, baz].every(is("apple"))) {
console.log("foo, bar, and baz are apple");
} else {
console.log("foo, bar, and baz are NOT apple");
}
is = (target, ...values) => values.every(x => x === target) so you can call it as if (is("apple", foo, bar, baz)) but it's still using an array in the end. Comparison operators take two arguments only - on the left side and the right side, then return a single value, so you can't chain them in any useful way.A solution is to wrap all the variables into an array and to use Array.every():
if ([foo, bar].every((val) => val === 'apple')) {
...
}
It is good if you need to check 5-6 values or more but for only two values I think your original code is easier to read.
You can set a variable and check against the variable if you don´t want to repeat your self.
let value = 'apple';
if(foo === value && bar === value){then do something}
note: better to rename value to a name that represent your variable better in your problem domain.
