空白上的仅 Javascript 自动换行功能？

Question

Most wordwrap functions I've found are bound to css and/or a browser dom. I'm working in a javascript environment (rhino) and need to find or design a better word wrap that breaks on whitespace before a given line length value. My current solution just searches for the last white space before the given character, then clips the left side, storing it as a line of output (in an array return). Repeat until no more text remains.

Hoping someone has seen something elegant.

Answer 1

You could write something like:

let wordwrapped = (original + ' ').replace(/(\S(.{0,78}\S)?)\s+/g, '$1\n').trim();

That will replace \\s+ with \\n after at-least-one,-at-most-eighty,-preferably-as-many-as-possible characters. (Note: if there are more than eighty characters in a row without whitespace, then there will be a line-break before and after them, but no wrapping will take place inside them.)

See it in action:

 // generate random sequence of 500 letters and spaces: let original = String.fromCharCode.apply(String, Array.from({length: 500}, () => 64 + Math.floor(Math.random() * 27))).replace(/@/g, ' '); // perform word-wrapping: let wordwrapped = (original + ' ').replace(/(\\S(.{0,78}\\S)?)\\s+/g, '$1\\n').trim(); // show the results in the <pre> elements: document.getElementById('ruakh-original').innerText = 'original:\\n' + original; document.getElementById('ruakh-word-wrapped').innerText = 'word-wrapped:\\n' + wordwrapped;

 <pre id="ruakh-original"></pre> <pre id="ruakh-word-wrapped"></pre>

Answer 2

This regex will wrap every 0-width character and respect whitespaces and hyphens also cuts words longer than width characters. Try it out on regexr .

/**
 * Wrap every 0-`width` character and respect whitespaces and hyphens also cuts words longer than `width` characters.
 * @param str The string to wrapped
 * @param width The maximum length a string can be
 */
function wordwrap(str, width) {
    return str.replace(new RegExp(`(?:\\S(?:.{0,${width}}\\S)?(?:\\s+|-|$)|(?:\\S{${width}}))`, 'g'), s => `${s}\n`).slice(0, -1);
}

 function wordwrap(str, width) { return str.replace(new RegExp('(?:\\\\S(?:.{0,' + width + '}\\\\S)?(?:\\\\s+|-|$)|(?:\\\\S{' + width + '}))', 'g'), function (s) {return s + '\\n'}).slice(0, -1); } console.log(wordwrap('This is my regular-expression. It will wrap every 0-20 character and respect whitespaces and hyphens, also cuts reallylongwordslikethis.', 20));

Answer 3

RegEx is really the way to go. /.{0,79}(?:\\s|$)/g will grab the longest line under 80 characters ending with a character or the end of the file. Calling exec multiple times will extract each line.

var text = "";
var regex = /.{0,79}(?:\s|$)/g;
var lines = [];
var line;

while (line = regex.exec(text)) {
    lines.push(line);
}