javascript - 不要将 br 和 nbsp 计入字符串中

Question

我有一个由“br”和“nbsp;”组成的字符串标签，我需要的是我需要将字符限制为 100，这意味着只应显示 100 个字符，因为每个“br”需要 4 个字符而不是 100 个字符，我得到 108，要低于输出我可以这样做单行

data.substr(0,100) 

输出=>

it to make a type specimen book.

It has survived not only five centuries, but also the leap

但它包含 br 标签，我不想删除 br 和 nbsp；但不要算这个

预期输出=>

it to make a type specimen book.

It has survived not only five centuries, but also the leap into ele

我已经做了一些片段，但它给出的计数是 108

var data = `it to make a type specimen book. <br><br>It has survived not only five centuries, but also the leap into electronic typesetting, <br><br>remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages<br><br>, and more recently with desktop publishing software like Aldus PageMaker including&nbsp; versions of Lorem Ipsum.`
// removes nbsp
var docDesc = data.replace(/[&]nbsp[;]/gi," "); 
// removes br
var stringData = docDesc.replace(/[<]br[^>]*[>]/gi,""); 
var subData =  stringData.substr(0,100)
function test(subData) {
    
	var n = subData.split(" ");
    
	return n.slice(Math.max(n.length - 5, 1))


}
var lastData = test(subData);
var lastString = lastData.join(" ")
var finalData = data.substring(0,data.indexOf(lastString)) + lastString

console.log(finalData)
console.log(finalData.length)

Answer 1

在最简单的形式中，您可以编写一个类似于子字符串但排除一些“单词”的函数，如下所示:

function substringWithExcludes(str, excludes, length) {
    let idx = 0;
    let len = 0;

    while(idx < str.length && len < length){
        let match = false;

        for(let exclude of excludes) {
            if(str.startsWith(exclude, idx)) {
                idx += exclude.length;
                match = true;
                break;
            }
        }

        if(!match) {
            len++;
            idx++;
        }
    }

    return str.substring(0, idx);
}

这被称为:

const data = `it to make a type specimen book. <br>\r\n<br>\r\nIt has survived not only five centuries, but also the leap into electronic typesetting, <br>\r\n<br>\r\nremaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages<br>\r\n<br>\r\n, and more recently with desktop publishing software like Aldus PageMaker including&nbsp; versions of Lorem Ipsum.`;

const result = substringWithExcludes(data, ["\r", "\n", "&nbsp;", "<br>"], 100);

len跟踪没有 <br> 的字符串长度所有这一切，同时 idx包括这些比赛。对于每个排除，我们需要做的是首先查看它是否匹配，以及是否将长度添加到 idx 。如果不匹配，则需要包含一个有效字符(同时增加 len 和 idx )。

对于大型 length 可能会很慢还有很多excludes ，但它完成了工作。您可以添加不区分大小写的特定情况，并且 <br />必要时进行匹配。 startsWith需要时可以与正则表达式匹配交换。