用于循环查找之前，等于，之间和之后值的Javascript？

Question

我觉得我遗漏了一些明显的东西。这是一个简单的例子来说明我的问题。

我希望 current = 3 返回“之前”。 current = 4 应该返回“key-two”，current = 5 应该返回“between”，current = 7 应该返回“key-two”，current = 8 应该返回“after”。

此代码未按预期工作。将电流设置为 7 返回“key-two”，将其设置为 8 或更大返回“after”将其设置为任何其他数字返回之间。

let items = []
items['key-one'] = 4
items['key-two'] = 7

let current = 3

let results = ''

for(let key in items) {
    let keyOne = ''
    let keyTwo = ''
    if (key === 'key-one') {
        keyOne = items[key]
    }
    if (key === 'key-two') {
        keyTwo = items[key]
    }
    if (current < keyOne) {
        results = 'before'
    }
    else if (current === items[key]) {
        results = key
    }
    else if (current > keyOne && current < keyTwo) {
        results = 'between'
    }
    else if (current > keyTwo) {
        results = 'after'
    }
}
document.write(results)

Answer 1

每次循环迭代时，您都有效地创建了一个新变量。将 keyOne 和 keyTwo 放在循环之外。

let items = []
items['key-one'] = 4
items['key-two'] = 7

let current = 3

let results = ''
let keyOne = ''
let keyTwo = ''
    
for(let key in items) {

    if (key === 'key-one') {
        keyOne = items[key]
    }
    if (key === 'key-two') {
        keyTwo = items[key]
    }
    if (current < keyOne) {
        results = 'before'
    }
    else if (current === items[key]) {
        results = key
    }
    else if (current > keyOne && current < keyTwo) {
        results = 'between'
    }
    else if (current > keyTwo) {
        results = 'after'
    }
}
document.write(results)

这足以让您现有的代码正常工作，但还有很多可以改进的地方。考虑这个方法..

function positionInRange(point, low, high){
  return point > high ? "after" :
    point < low ? "before" :
    point > low && point < high ? "between" :
    point == low ? "key-1" : "key-2"
}

var items = {
  "key-1": 4,
  "key-2": 7
}

var results = positionInRange(3, items['key-1'], items['key-2']);
document.write(results)