26個Jquery使用小技巧

Web開發者發表於2012-09-05
jQuery

下面列出了一些Jquery使用技巧。比如有禁止右鍵點選、隱藏搜尋文字框文字、在新視窗中開啟連結、檢測瀏覽器、預載入圖片、頁面樣式切換、所有列等高、動態控制頁面字型大小、獲得滑鼠指標的X值Y值、驗證元素是否為空、替換元素、延遲載入、驗證元素是否存在於Jquery集合中、使DIV可點選、克隆物件、使元素居中、計算元素個數、使用Google主機上的Jquery類庫、禁用Jquery效果、解決Jquery類庫與其他Javascript類庫衝突問題。

1. 禁止右鍵點選

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$(document).ready(function(){
    $(document).bind("contextmenu",function(e){
        return false;
    });
});

2. 隱藏搜尋文字框文字

Hide when clicked in the search field, the value.(example can be found below in the comment fields)

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$(document).ready(function() {
$("input.text1").val("Enter your search text here");
   textFill($('input.text1'));
});
  
    function textFill(input){ //input focus text function
    var originalvalue = input.val();
    input.focus( function(){
        if( $.trim(input.val()) == originalvalue ){ input.val(''); }
    });
    input.blur( function(){
        if( $.trim(input.val()) == '' ){ input.val(originalvalue); }
    });
}

3. 在新視窗中開啟連結

XHTML 1.0 Strict doesn’t allow this attribute in the code, so use this to keep the code valid.

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$(document).ready(function() {
   //Example 1: Every link will open in a new window
   $('a[href^="http://"]').attr("target", "_blank");
  
   //Example 2: Links with the rel="external" attribute will only open in a new window
   $('a[@rel$='external']').click(function(){
      this.target = "_blank";
   });
});
// how to use
<A href="http://www.opensourcehunter.com" rel=external>open link</A>

4. 檢測瀏覽器

注: 在版本jQuery 1.4中，$.support 替換掉了$.browser 變數

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$(document).ready(function() {
// Target Firefox 2 and above
if ($.browser.mozilla && $.browser.version >= "1.8" ){
    // do something
}
 
// Target Safari
if( $.browser.safari ){
    // do something
}
 
// Target Chrome
if( $.browser.chrome){
    // do something
}
 
// Target Camino
if( $.browser.camino){
    // do something
}
 
// Target Opera
if( $.browser.opera){
    // do something
}
 
// Target IE6 and below
if ($.browser.msie && $.browser.version <= 6 ){
    // do something
}
 
// Target anything above IE6
if ($.browser.msie && $.browser.version > 6){
    // do something
}
});

5. 預載入圖片

This piece of code will prevent the loading of all images, which can be useful if you have a site with lots of images.

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$(document).ready(function() {
jQuery.preloadImages = function()
{
  for(var i = 0; i<ARGUMENTS.LENGTH; jQuery(?<img { i++)>").attr("src", arguments[i]);
  }
}
// how to use
$.preloadImages("image1.jpg");
});

6. 頁面樣式切換

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$(document).ready(function() {
    $("a.Styleswitcher").click(function() {
        //swicth the LINK REL attribute with the value in A REL attribute
        $('link[rel=stylesheet]').attr('href' , $(this).attr('rel'));
    });
// how to use
// place this in your header
<LINK rel=stylesheet type=text/css href="default.css">
// the links
<A class="Styleswitcher" href="#" rel=default.css>Default Theme</A>
<A class="Styleswitcher" href="#" rel=red.css>Red Theme</A>
<A class="Styleswitcher" href="#" rel=blue.css>Blue Theme</A>
});

7. 列高度相同

如果使用了兩個CSS列，使用此種方式可以是兩列的高度相同。

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$(document).ready(function() {
function equalHeight(group) {
    tallest = 0;
    group.each(function() {
        thisHeight = $(this).height();
        if(thisHeight > tallest) {
            tallest = thisHeight;
        }
    });
    group.height(tallest);
}
// how to use
$(document).ready(function() {
    equalHeight($(".left"));
    equalHeight($(".right"));
});
});

8. 動態控制頁面字型大小

使用者可以改變頁面字型大小

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$(document).ready(function() {
  // Reset the font size(back to default)
  var originalFontSize = $('html').css('font-size');
    $(".resetFont").click(function(){
    $('html').css('font-size', originalFontSize);
  });
  // Increase the font size(bigger font0
  $(".increaseFont").click(function(){
    var currentFontSize = $('html').css('font-size');
    var currentFontSizeNum = parseFloat(currentFontSize, 10);
    var newFontSize = currentFontSizeNum*1.2;
    $('html').css('font-size', newFontSize);
    return false;
  });
  // Decrease the font size(smaller font)
  $(".decreaseFont").click(function(){
    var currentFontSize = $('html').css('font-size');
    var currentFontSizeNum = parseFloat(currentFontSize, 10);
    var newFontSize = currentFontSizeNum*0.8;
    $('html').css('font-size', newFontSize);
    return false;
  });
});

9. 返回頁面頂部功能

For a smooth(animated) ride back to the top(or any location).

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$(document).ready(function() {
$('a[href*=#]').click(function() {
 if (location.pathname.replace(/^\//,'') == this.pathname.replace(/^\//,'')
 && location.hostname == this.hostname) {
   var $target = $(this.hash);
   $target = $target.length && $target
   || $('[name=' + this.hash.slice(1) +']');
   if ($target.length) {
  var targetOffset = $target.offset().top;
  $('html,body')
  .animate({scrollTop: targetOffset}, 900);
    return false;
   }
  }
  });
// how to use
// place this where you want to scroll to
<A name=top></A>
// the link
<A href="#top">go to top</A>
});

11. 獲得滑鼠指標ＸＹ值

Want to know where your mouse cursor is?

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$(document).ready(function() {
   $().mousemove(function(e){
     //display the x and y axis values inside the div with the id XY
    $('#XY').html("X Axis : " + e.pageX + " | Y Axis " + e.pageY);
  });
// how to use
<DIV id=XY></DIV>
 
});

12. 驗證元素是否為空

This will allow you to check if an element is empty.

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$(document).ready(function() {
  if ($('#id').html()) {
   // do something
   }
});

13. 替換元素

Want to replace a div, or something else?

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$(document).ready(function() {
   $('#id').replaceWith('
<DIV>I have been replaced</DIV>
 
');
});

14. jQuery延時載入功能

Want to delay something?

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$(document).ready(function() {
   window.setTimeout(function() {
     // do something
   }, 1000);
});

15. 移除單詞功能

Want to remove a certain word(s)?

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$(document).ready(function() {
   var el = $('#id');
   el.html(el.html().replace(/word/ig, ""));
});

16. 驗證元素是否存在於jquery物件集合中

Simply test with the .length property if the element exists.

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$(document).ready(function() {
   if ($('#id').length) {
  // do something
  }
});

17. 使整個DIV可點選

Want to make the complete div clickable?

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$(document).ready(function() {
    $("div").click(function(){
      //get the url from href attribute and launch the url
      window.location=$(this).find("a").attr("href"); return false;
    });
// how to use
<DIV><A href="index.html">home</A></DIV>
 
});

18. ID與Class之間轉換.

當改變Window大小時，在ID與Class之間切換

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$(document).ready(function() {
   function checkWindowSize() {
    if ( $(window).width() > 1200 ) {
        $('body').addClass('large');
    }
    else {
        $('body').removeClass('large');
    }
   }
$(window).resize(checkWindowSize);
});

19. 克隆物件

Clone a div or an other element.

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$(document).ready(function() {
   var cloned = $('#id').clone();
// how to use
<DIV id=id></DIV>
 
});

20. 使元素居螢幕中間位置

Center an element in the center of your screen.

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$(document).ready(function() {
  jQuery.fn.center = function () {
      this.css("position","absolute");
      this.css("top", ( $(window).height() - this.height() ) / 2+$(window).scrollTop() + "px");
      this.css("left", ( $(window).width() - this.width() ) / 2+$(window).scrollLeft() + "px");
      return this;
  }
  $("#id").center();
});

21. 寫自己的選擇器

Write your own selectors.

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$(document).ready(function() {
   $.extend($.expr[':'], {
       moreThen1000px: function(a) {
           return $(a).width() > 1000;
      }
   });
  $('.box:moreThen1000px').click(function() {
      // creating a simple js alert box
      alert('The element that you have clicked is over 1000 pixels wide');
  });
});

22. 統計元素個數

Count an element.

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$(document).ready(function() {
   $("p").size();
});

23. 使用自己的 Bullets

Want to use your own bullets instead of using the standard or images bullets?

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$(document).ready(function() {
   $("ul").addClass("Replaced");
   $("ul > li").prepend("‒ ");
 // how to use
 ul.Replaced { list-style : none; }
});

24. 引用Google主機上的Jquery類庫

Let Google host the jQuery script for you. This can be done in 2 ways.

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//Example 1
<SCRIPT src="http://www.google.com/jsapi"></SCRIPT>
<SCRIPT type=text/javascript>
google.load("jquery", "1.2.6");
google.setOnLoadCallback(function() {
    // do something
});
</SCRIPT><SCRIPT type=text/javascript src="http://ajax.googleapis.com/ajax/libs/jquery/1.2.6/jquery.min.js"></SCRIPT>
 
 // Example 2:(the best and fastest way)
<SCRIPT type=text/javascript src="http://ajax.googleapis.com/ajax/libs/jquery/1.2.6/jquery.min.js"></SCRIPT>

25. 禁用Jquery（動畫）效果

Disable all jQuery effects

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$(document).ready(function() {
    jQuery.fx.off = true;
});

26. 與其他Javascript類庫衝突解決方案

To avoid conflict other libraries on your website, you can use this jQuery Method, and assign a different variable name instead of the dollar sign.

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$(document).ready(function() {
   var $jq = jQuery.noConflict();
   $jq('#id').show();
});

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