經常使用代碼段

1. 判斷日期是否有效

function isValidDate(value, userFormat) {

  // Set default format if format is not provided
  userFormat = userFormat || 'mm/dd/yyyy';

  // Find custom delimiter by excluding
  // month, day and year characters
  var delimiter = /[^mdy]/.exec(userFormat)[0];

  // Create an array with month, day and year
  // so we know the format order by index
  var theFormat = userFormat.split(delimiter);

  // Create array from user date
  var theDate = value.split(delimiter);

  function isDate(date, format) {
    var m, d, y, i = 0, len = format.length, f;
    for (i; i < len; i++) {
      f = format[i];
      if (/m/.test(f)) m = date[i];
      if (/d/.test(f)) d = date[i];
      if (/y/.test(f)) y = date[i];
    }
    return (
      m > 0 && m < 13 &&
      y && y.length === 4 &&
      d > 0 &&
      // Check if it's a valid day of the month
      d <= (new Date(y, m, 0)).getDate()
    );
  }

  return isDate(theDate, theFormat);
}

2.高亮文本

function highlight(text, words, tag) {

  // Default tag if no tag is provided
  tag = tag || 'span';

  var i, len = words.length, re;
  for (i = 0; i < len; i++) {
    // Global regex to highlight all matches
    re = new RegExp(words[i], 'g');
    if (re.test(text)) {
      text = text.replace(re, '<'+ tag +' class="highlight">$&</'+ tag +'>');
    }
  }

  return text;
}

4 限制文本字數
function excerpt(str, nwords) {
var words = str.split(' ');
words.splice(nwords, words.length-1);
return words.join(' ') +
(words.length !== str.split(' ').length ? '…' : '');
}

高效簡潔 判斷瀏覽器類型及版本代碼 ，親測！

var ua = navigator.userAgent.toLowerCase();
    var s;

    (s = ua.match(/rv:([\d.]+)\) like gecko/)) ? Sys.ie = s[1] :
    (s = ua.match(/msie ([\d.]+)/)) ? Sys.ie = s[1] :
    (s = ua.match(/firefox\/([\d.]+)/)) ? Sys.firefox = s[1] :
    (s = ua.match(/chrome\/([\d.]+)/)) ? Sys.chrome = s[1] :
    (s = ua.match(/opera.([\d.]+)/)) ? Sys.opera = s[1] :
    (s = ua.match(/version\/([\d.]+).*safari/)) ? Sys.safari = s[1] : 0;
    
    if (Sys.ie) console.log('IE: ', Sys.ie);
    if (Sys.firefox) console.log('Firefox: ', Sys.firefox);
    if (Sys.chrome) console.log('Chrome: ', Sys.chrome);
    if (Sys.opera) console.log('Opera: ', Sys.opera);
    if (Sys.safari) console.log('Safari: ', Sys.safari);