Javascript中带有HTML标签的子字符串文本

Taking into consideration that parsing html with regex is a bad idea, here is a solution that does just that :)

要明确一点:这不是一个有效的解决方案，它的目的是对输入字符串做出非常宽松的假设，因此应该谨慎对待.阅读上面的链接，看看为什么永远无法使用正则表达式解析 html.

function htmlSubstring(s, n) {
    var m, r = /<([^>s]*)[^>]*>/g,
        stack = [],
        lasti = 0,
        result = '';

    //for each tag, while we don't have enough characters
    while ((m = r.exec(s)) && n) {
        //get the text substring between the last tag and this one
        var temp = s.substring(lasti, m.index).substr(0, n);
        //append to the result and count the number of characters added
        result += temp;
        n -= temp.length;
        lasti = r.lastIndex;

        if (n) {
            result += m[0];
            if (m[1].indexOf('/') === 0) {
                //if this is a closing tag, than pop the stack (does not account for bad html)
                stack.pop();
            } else if (m[1].lastIndexOf('/') !== m[1].length - 1) {
                //if this is not a self closing tag than push it in the stack
                stack.push(m[1]);
            }
        }
    }

    //add the remainder of the string, if needed (there are no more tags in here)
    result += s.substr(lasti, n);

    //fix the unclosed tags
    while (stack.length) {
        result += '</' + stack.pop() + '>';
    }

    return result;

}

示例: http://jsfiddle.net/danmana/5mNNU/

注意:patrick dw 的解决方案可能是对坏 html 更安全，但我不确定它处理空格的效果如何.