一、要求

// Write a function that takes an array of numbers as argument
// Convert the array to an object
// It should have a key for each unique value of the array
// The corresponding object value should be the number of times the key occurs within the array

二、解

function myFunction(a) {
    
    return a.reduce((acc, cur) => {
    
        return {
     ...acc, [cur]: acc[cur] + 1 || 1 };
    }, {
    })
}

还可以通过遍历数组，然后依次将数组的值作为对象的属性，然后通过计算次数，但是远不如reduce优雅。