一种方法如下(使用纯 JavaScript,尽管您需要使用最新的浏览器):
// first, we need to get all the 'li' items:
var lis = document.querySelectorAll('ul > li'),
// find the relevant text-property for this browser:
textProp = 'textContent' in document ? 'textContent' : 'innerText',
// empty string variable to allow assessment of changes:
_newText = '';
// Remap the bullet list entries to a new (consistent) tag type (your choice – make it look pretty!).
// do this one yourself.
// a function to zero-pad the numbers (I believe a requirement of Dewey Decimal):
function leftPadNumber(num, numLength, padChar) {
var nString = num.toString(),
major = parseInt(num, 10),
minor = parseFloat(nString.substring(nString.indexOf('.'))),
diff = numLength - major.toString().length;
if (diff > 0) {
return new Array(diff + 1).join(padChar || 0) + (major + minor);
} else {
return num;
}
}
// For entries between 100 and 200, add 100 to the Dewey decimal number.
// For entries between 400 and 500, add 200 to the Dewey decimal number.
// Entries between 850 and 900 need to have 100 removed from the Dewey decimal number.
// Entries between 600 and 650 need to have 17 added to the Dewey decimal number
// note that I've taken a very literal interpretation of 'between' (amend if necessary):
function amendedDeweyDecimal(num) {
if (num > 100 && num < 200) {
num += 100;
} else if (num > 400 && num < 500) {
num += 200;
} else if (num > 850 && num < 900) {
num -= 100;
} else if (num > 600 && num < 650) {
num += 17;
}
// happens if num falls somewhere outside of the above constraints:
return num;
}
// iterates over each element in the 'lis' nodeList/collection:
[].forEach.call(lis, function (a) {
/* replaces the found numbers ('m') in the string, using the two
functions, above, and assigns those to the _newText variable:
_newText = a[textProp].replace(/(\d{3}\.\d{2})/, function (m) {
return leftPadNumber(amendedDeweyDecimal(parseFloat(m)).toFixed(2), 3);
});
// For items that get changed, append “changed” to the record.
// For items that do not get changed, append “no change” to the record.
// returns the original text to the element, along with '(no change)'
// (if 'a[textProp]' is exactly equal to '_newText') or with '(changed)'
// (if the two variables are not identical):
a[textProp] = _newText + ' (' + (_newText === a[textProp] ? 'no change' : 'changed') + ')';
});
// For records that are incorrect, append “invalid record” to the record
// I have absolutely no idea how to assess an 'incorrect' record.
JS 小提琴演示。
参考: