javascript - 无法让 Javascript 函数在演示中运行

Question

function trim(str,options){
  var   string = str.replace(/^\s\s*/, ''),
        ws = /\s/,
        i = str.length,
        j = -1;
  if(options==="begin"){while(ws.test(string.charAt(++j)));return string.slice(j,i);}
  if(options==="end"){while(ws.test(string.charAt(--i)));return string.slice(j+1,i+1);}
  while(ws.test(string.charAt(--i)));while(ws.test(string.charAt(++j)));
  return string.slice(j, i + 1);
}

此函数是 C# 中 Trim() 方法的实现。

我添加了用于删除开头和结尾处的空格的选项。问题是，我无法让它在演示中工作。

我所做的是:

var a = "           zareaerar  arzare        ";
var b = "aezze          azeze      a    ";
var c = "azrazza rzrzrzrp"
var d = " aezzaeazeazeaz         azez ";

document.write('<p style="backround:#ff0000">',trim(a,"begin"),'</p>','<br />');
document.write('<p style="backround:#ff0000">',trim(b,"begin"),'</p>','<br />');
document.write('<p style="backround:#ff0000">',trim(c,"begin"),'</p>','<br />');
document.write('<p style="backround:#ff0000">',trim(d,"begin"),'</p>','<br />');

首先，没有出现背景颜色，并且字符串似乎也失去了字符串中间的空格......

这仅适用于用户输入吗？现在字符串会自动 trim 吗？

Answer 1

1) 由于拼写错误，您没有看到背景:backround 而不是 background

2) 在 HTML 中，多个空格没有任何意义。如果要在段落中的单词之间插入不间断的空格，则需要使用  。

Reference (W3 spec) :

Note that a sequence of white spaces between words in the source document may result in an entirely different rendered inter-word spacing (except in the case of the PRE element). In particular, user agents should collapse input white space sequences when producing output inter-word space. This can and should be done even in the absence of language information (from the lang attribute, the HTTP "Content-Language" header field (see [RFC2616], section 14.12), user agent settings, etc.).

The PRE element is used for preformatted text, where white space is significant.