reactjs - 你如何在 React 中截断 html 文本？

Question

我正在尝试将以下 html 截断为 5 个字符:

<b>Hello</b> how are you today?

我要找的结果是:

您好

但是，如何忽略截断中的 html 标记，以免导致以下结果？

<b>He

我正在使用一个 html 解析器，所以我不能在使用它之后截断字符串。这是我的代码，不用说，它不起作用!

import React from 'react';
import parse from 'html-react-parser';
import Typography from '@material-ui/core/Typography';


const Message= () => {
  const message= "<b>Hello</b> how are you today?"
  const messageParsed = parse(message);

  return (
          <Typography variant="body2">
            {messageParsed.substr(0, 5)}
          </Typography>
  );
};

export default Message;

什么是正确的做法？

非常感谢，

凯蒂

Answer 1

您可以使用 Range 来保持 html 结构

要获取特定长度的 html，请调用下面的 htmlToLength(html, length)。

您还可以通过调用 htmlToNodeWithLength(html, length) 获取 DocumentFragment。

该算法的核心是findRangeWithLength(range, length)，它从末尾(递归)缩小range，直到它具有给定的长度。

function htmlToLength(html, length) {
  const trimmedNode = htmlToNodeWithLength(html, length);

  const container = document.createElement("div");
  container.appendChild(trimmedNode);
  return container.innerHTML;
}

function htmlToNodeWithLength(html, length) {
  // Only for measurement. Never added to DOM.
  const container = document.createElement("div");
  container.innerHTML = html;

  const fullRange = document.createRange();
  fullRange.setStart(container, 0);
  fullRange.setEnd(container, 1);

  const range = findRangeWithLength(fullRange, length);
  return range.cloneContents();
}

function findRangeWithLength(range, length) {
  if (rangeLength(range) < length) return range;

  // Find the childNode with at least length content.
  for (const childNode of range.endContainer.childNodes) {
    range.setEnd(childNode, lastEndOffset(childNode));
    if (rangeLength(range) >= length) {
      return findRangeWithLength(range, length);
    }
  }

  // There are no child nodes long enough. It's a text node.
  const diff = length - rangeLength(range) + range.endOffset;
  range.setEnd(range.endContainer, diff);
  return range;
}

function lastEndOffset(node) {
  return node.childNodes.length || node.textContent.length;
}

function rangeLength(range) {
  return range.toString().length;
}

const html = "<p>No <span></span><b>Hello</b> <i>World</i></p>";
const length = 7;
const trimmedNode = htmlToNodeWithLength(html, length);

document.querySelector(".raw-input").textContent = html;
document.querySelector(".trimmed").appendChild(trimmedNode);
document.querySelector(".length").textContent = length;
document.querySelector(".input").innerHTML = html;
document.querySelector(".raw-output").textContent = htmlToLength(html, length);

<h2>Raw HTML input</h2>
<div class="raw-input"></div>
<h2>Rendered Input</h2>
<div class="input"></div>
<h2>Rendered output to length <span class="length">?</span></h2>
<div class="trimmed"></div>
<h2>Raw HTML output</h2>
<div class="raw-output"></div>