There's a similar question for LINQ: Is there an equivalent of None() in LINQ?
There are some boolean methods on collections / arrays:
Array.some (similar to linq.Any)Array.every (similar to linq.All)Can I check if no elements in array match a given function callback
A possible workaround is to .filter and then check .length and make sure it's zero:
let arr = ["a","b","c"]
// make sure that no item in array = "b"
let noBs = arr.filter(el => el === "b").length === 0
As logically concluded by the linq example
Noneis the same as!Any, so you could define your own extension method as follows:
let none = (arr, callback) => !arr.some(callback)
And then call like this:
let arr = ["a","b","c"]
let noBs = none(arr, el => el === "b")
Or if you want to extend Array.proto, you can add the following method:
Object.defineProperty(Array.prototype, 'none', {
value: function (callback) { return !this.some(callback) }
});
Then call like this:
let arr = ["a","b","c"]
let noBs = arr.none(el => el === "b")
Not at the moment
At the moment I'm using an Array.some() and then negating the whole thing
Personally I think an Array.none function would be awesome
You could request it to be added to the next release of ECMA. It looks like a bit of a process to say the least but if we wanted to get this added to ECMA this would be the way.
Liked the @KyledMit approach. On the similar lines, using the findIndex is another way. (find may not be reliable as we can not check on return value).
const arr = ["a","b","c"]
const noBs = arr.findIndex(el => el === "b") < 0;
console.log(noBs)
If it's an array with scalar values, you can use Array.prototype.includes()
const arr = ["a", "b", "c"]
const includesB = arr.includes("b")
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/includes
