javascript - sort() 在 mozilla 和 opera 中无法正常工作

Question

我需要对一个数组进行排序，但它只能在 Chrome 中正常工作。在 mozilla 规范中我找到了这段文字，但仍然无法解决这个问题:

"The elements of this array are sorted. The sort is not necessarily stable (that is, elements that compare equal do not necessarily remain in their original order). If comparefn is not undefined, it should be a function that accepts two arguments x and y and returns a negative value if x < y, zero if x = y, or a positive value if x > y."

和这个链接https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Array/sort也许它会对你和我有所帮助

这是我的代码

arr.sort(sortTrip); 

function sortTrip(a, b) {   

    if (a.to != b.from) return 1;
    if (a.to == b.from) return -1;

}

这是arr:

var arr = [
    {
        "from": "Moscow",
        "to": "Rome",
        "transport": "NSB Regiontog Train",
        "seat": "25"
    },
    {
        "from": "Oslo",
        "to": "Paris",
        "transport": "NSB Regiontog Train",
        "seat": "25"
    },
    {
        "from": "Helsinki",
        "to": "Tokio",
        "transport": "NSB Regiontog Train",
        "seat": "25"
    },
    {
        "from": "Tokio",
        "to": "Moscow",
        "transport": "NSB Regiontog Train",
        "seat": "25"
    },
    {
        "from": "Paris",
        "to": "New-York",
        "transport": "NSB Regiontog Train",
        "seat": "25"
    },
    {
        "from": "Rome",
        "to": "Oslo",
        "transport": "NSB Regiontog Train",
        "seat": "25"
    }
]

结果必须是

• 赫尔辛基 - 东京
• 东京 - 莫斯科
• 莫斯科 - 罗马
• 罗马 - 奥斯陆
• 奥斯陆 - 巴黎
• 巴黎 - 纽约

Answer 1

See also Sorting in JavaScript: Should every compare function have a "return 0" statement?

<小时/>

if (a.to != b.from) return 1;
if (a.to == b.from) return -1;

这不是一个一致的比较函数(违反了自反性，例如 compare(x, x) == 0 )。您希望它做什么？

引用ES5.1 spec on sort :

If comparefn is […] not a consistent comparison function for the elements of this array, the behaviour of sort is implementation-defined.

A function comparefn is a consistent comparison function for a set of values S if all of the requirements below are met for all values a, b, and c (possibly the same value) in the set S: The notation a <CF b means comparefn(a,b) < 0; a =CF b means comparefn(a,b) = 0 (of either sign); and a >CF b means comparefn(a,b) > 0.

Calling comparefn(a,b) always returns the same value v when given a specific pair of values a and b as its two arguments. Furthermore, Type(v) is Number, and v is not NaN. Note that this implies that exactly one of a <CF b, a =CF b, and a >CF b will be true for a given pair of a and b.

• Calling comparefn(a,b) does not modify the this object.
• a =CF a (reflexivity)
• If a =CF b, then b =CF a (symmetry)
• If a =CF b and b =CF c, then a =CF c (transitivity of =CF)
• If a <CF b and b <CF c, then a <CF c (transitivity of <CF)
• If a >CF b and b >CF c, then a >CF c (transitivity of >CF)

NOTE: The above conditions are necessary and sufficient to ensure that comparefn divides the set S into equivalence classes and that these equivalence classes are totally ordered.