javascript中的序数

问题描述

有没有什么优雅的方法可以在 js/coffee 中获取 word 格式的序数?像这样的:

Is there any elegant way how to get ordinals in word format in js/coffee? Something like this:

ordinalInWord(1) # => "first"
ordinalInWord(2) # => "second"
ordinalInWord(5) # => "fifth"

推荐答案

恐怕序数不够规则，无法避免将它们逐个打出来.

I'm afraid the ordinals aren't regular enough to avoid typing each of them out.

function ordinalInWord( cardinal ) {
    var ordinals = [ 'zeroth', 'first', 'second', 'third' /* and so on */ ];

    return ordinals[ cardinal ];
}

如果您需要该功能在 20 岁以后工作，您可以利用出现的模式:

If you need the function work past 20, you can take advantage of the pattern that emerges:

function ordinalInWord( cardinal ) {
    var ordinals = [ 'zeroth', 'first', 'second', 'third' /* and so on up to "twentieth" */ ];
    var tens = {
        20: 'twenty',
        30: 'thirty',
        40: 'forty' /* and so on up to 90 */
    };
    var ordinalTens = {
        30: 'thirtieth',
        40: 'fortieth',
        50: 'fiftieth' /* and so on */
    };

    if( cardinal <= 20 ) {                    
        return ordinals[ cardinal ];
    }

    if( cardinal % 10 === 0 ) {
        return ordinalTens[ cardinal ];
    }

    return tens[ cardinal - ( cardinal % 10 ) ] + ordinals[ cardinal % 10 ];
}

演示:http://jsfiddle.net/AQCqK/

将其扩展到超过 99 应该不难.

Expanding that to work past 99 shouldn't be difficult.

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