欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页

【转】项目中遇到的bug(web前端-持续更新)

程序员文章站 2022-05-11 10:51:47
...

写代码容易遇到各种奇怪的BUG,推荐使用Fundebug做线上bug实时监控。


input放在a标签里面单击不能获取input的光标(IE环境下)

双击才可以获得焦点,目前有的解决方案:

  • 不要给a标签添加href属性;

  • 不要在外面套上a标签。

隐藏input标签的光标

项目需求:input值json加载,只读+光标隐藏,通用的解决方案有其他标签模拟,但是不能改input 
所以解决方案为给input加下面这两个属性:

//只读 
readonly="readonly" 
//隐藏光标
unselectable="on"

返回私有数组

返回数组的一个副本,这样改动就不会影响原数组,只是副本而已

    var array = (function () {
       var days = ['Mo', 'Tu', 'We', 'Th', 'Fr', 'Sa', 'Su'];
        return {
            getDays: function () {
                return days.slice();
            }
        }
    })()

jquery选择器的扩展

//jQuery contains 选择器,对Contains查找的内容不区分大小写
jQuery.expr[':'].Contains = function (a, i, m) {
    return jQuery(a).text().toUpperCase()
        .indexOf(m[3].toUpperCase()) >= 0;
};

例子

<div>john</div>
<div>John</div>
<div>hey hey JOHN hey hey</div>
$('div:Contains("john")') //会选择到两个div

当一个变量被声明后,扩充其属性并不会改变原数据类型

var a = 'foo'; 
a[1] = 'O'; 
console.log(0.1+0.2==0.3||a); //'foo'

闭包是函数的嵌套定义,而不是函数的嵌套调用

function foo(){
    console.log(a);
}
function bar () {
    var a = 3; 
    foo(); 
}
var a = 2;
bar(); //2

DOMContentLoaded兼容IE9以下版本

//jQuery的实现

      // Mozilla, Opera and webkit nightlies currently support this event
      if ( document.addEventListener ) {
          // Use the handy event callback
          document.addEventListener( "DOMContentLoaded", DOMContentLoaded, false );

          // A fallback to window.onload, that will always work
          window.addEventListener( "load", jQuery.ready, false );

          // If IE event model is used
      } else if ( document.attachEvent ) {
          // ensure firing before onload,
          // maybe late but safe also for iframes
          document.attachEvent( "onreadystatechange", DOMContentLoaded );

          // A fallback to window.onload, that will always work
          window.attachEvent( "onload", jQuery.ready );

          // If IE and not a frame
          // continually check to see if the document is ready
          var toplevel = false;

          try {
              toplevel = window.frameElement == null;
          } catch(e) {}

          if ( document.documentElement.doScroll && toplevel ) {
              doScrollCheck();
          }
      }

        //函数DOMContentLoaded的赋值
        if ( document.addEventListener ) {
            DOMContentLoaded = function() {
                document.removeEventListener( "DOMContentLoaded", DOMContentLoaded, false );
                jQuery.ready();
            };

        } else if ( document.attachEvent ) {
            DOMContentLoaded = function() {
                // Make sure body exists, at least, in case IE gets a little overzealous (ticket #5443).
                if ( document.readyState === "complete" ) {
                    document.detachEvent( "onreadystatechange", DOMContentLoaded );
                    jQuery.ready();
                }
            };
        }

// The DOM ready check for Internet Explorer
        function doScrollCheck() {
            if ( jQuery.isReady ) {
                return;
            }

            try {
                // If IE is used, use the trick by Diego Perini
                // http://javascript.nwbox.com/IEContentLoaded/
                document.documentElement.doScroll("left");
            } catch(e) {
                setTimeout( doScrollCheck, 1 );
                return;
            }

            // and execute any waiting functions
            jQuery.ready();
        }

//网友的实现
    // @win window reference
    // @fn function reference
    function contentLoaded(win, fn) {

        var done = false, top = true,

                doc = win.document,
                root = doc.documentElement,
                modern = doc.addEventListener,

                add = modern ? 'addEventListener' : 'attachEvent',
                rem = modern ? 'removeEventListener' : 'detachEvent',
                pre = modern ? '' : 'on',

                init = function(e) {
                    if (e.type == 'readystatechange' && doc.readyState != 'complete') {
                        return;
                    }

                    //load事件在win上,移除事件监听(readystatechange, DOMContentLoaded, load)
                    (e.type == 'load' ? win : doc)[rem](pre + e.type, init, false);

                    //保证fn只执行一次
                    if (!done && (done = true)) fn.call(win, e || e.type);
                },

                poll = function() {
                    try { root.doScroll('left'); } catch(e) { setTimeout(poll, 50); return; }
                    init('poll');
                };

        if (doc.readyState == 'complete') fn.call(win, 'lazy');
        else {
            if (!modern && root.doScroll) {
                try { top = !win.frameElement; } catch(e) { }
                if (top) poll();
            }
            doc[add](pre + 'DOMContentLoaded', init, false); //触发时,doc.readyState为'interactive'
            doc[add](pre + 'readystatechange', init, false); //会触发两次,readystatechange先触发,再触发DOMContentLoaded, 最后才是load
            win[add](pre + 'load', init, false);
        }

    }

document.querySelectorAll和getElementsByTagName的区别

//html代码
<ul>
    <li>a</li>
    <li>b</li>
    <li>c</li>
</ul>

//script代码
    var ul = document.querySelector('ul');
    var li = ul.querySelectorAll('li'),
            tagLi = ul.getElementsByTagName('li'); //动态取值 
    ul.appendChild(document.createElement('li'));
    console.log(li.length); //3   li.toString()为[object NodeList]    console.log(tagLi.length); //4 tagLi.toString()为[object HTMLCollection]

版权声明:本文为吴孔云博客原创文章,转载请注明出处并带上链接,谢谢。https://blog.csdn.net/wkyseo/article/details/51159370

参考:

  1. Fundebug:小程序错误监控支持用户行为回溯
  2. 怪异的JavaScript系列(一)
  3. 怪异的JavaScript系列(二)

上一篇: html5表单验证

下一篇: HTML5表单