小于10加0到数字 [英] less than 10 add 0 to number

问题描述

如何修改此代码，以便在任何低于10的数字之前添加0

How can I modify this code to add a 0 before any digits lower than 10

$('#detect').html( toGeo(apX, screenX)  + latT +', '+ toGeo(apY, screenY) + lonT  );

function toGeo(d, max) {
   var c = '';

   var r = d/max * 180;
   var deg = Math.floor(r);
   c += deg + "° ";

   r = (r - deg) * 60;
   var min = Math.floor(r);
   c += min + "′ ";

   r = (r - min) * 60;
   var sec = Math.floor(r);
   c += sec + "″";

   return c;
}

所以输出将从

4°7'34W，168°1'23N

4° 7′ 34″W, 168° 1′ 23″N

到

04°07'34W，168°01'23N

04° 07′ 34″W, 168° 01′ 23″N

感谢您的时间

推荐答案

你可以随时

('0' + deg).slice(-2)

参见 slice（） ：

您也可以使用负数从数组的末尾进行选择

You can also use negative numbers to select from the end of an array

因此

('0' + 11).slice(-2) // '11'
('0' + 4).slice(-2)  // '04'

为了便于访问，您当然可以将其提取到函数中，甚至可以扩展 Number with it：

For ease of access, you could of course extract it to a function, or even extend Number with it:

Number.prototype.pad = function(n) {
    return new Array(n).join('0').slice((n || 2) * -1) + this;
}

这将允许你写：

c += deg.pad() + '° '; // "04° "

以上函数 pad 接受指定所需字符串长度的参数。如果没有使用这样的参数，它默认为2.您可以写：

The above function pad accepts an argument specifying the length of the desired string. If no such argument is used, it defaults to 2. You could write:

deg.pad(4) // "0045"

注意 n 不能高于11，因为0的字符串当前只有10个字符长。这当然可以给出技术解决方案，但我不想在这样一个简单的功能中引入复杂性。 （如果您选择，请参阅 alex的回答以获得优秀的解决方案）。

Note the obvious drawback that the value of n cannot be higher than 11, as the string of 0's is currently just 10 characters long. This could of course be given a technical solution, but I did not want to introduce complexity in such a simple function. (Should you elect to, see alex's answer for an excellent approach to that).

另请注意，您将无法编写 2.pad（）。它只适用于变量。但是，如果它不是变量，您将始终事先知道该数字包含多少位数。

Note also that you would not be able to write 2.pad(). It only works with variables. But then, if it's not a variable, you'll always know beforehand how many digits the number consists of.

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