Checks if all elements in an array are equal, based on the provided mapping function.
- Apply
fn
to the first element ofarr
. - Use
Array.prototype.every()
to check iffn
returns the same value for all elements in the array as it did for the first one. - Elements in the array are compared using the strict comparison operator, which does not account for
NaN
self-inequality.
代码实现
const allEqualBy = (arr, fn) => {
const eql = fn(arr[0]);
return arr.every(val => fn(val) === eql);
};
allEqualBy([1.1, 1.2, 1.3], Math.round); // true
allEqualBy([1.1, 1.3, 1.6], Math.round); // false
翻译自:https://www.30secondsofcode.org/js/s/function-based-array-element-equality