15 jQuery code snippets that you can use directly_jquery

An article you published "10 Super Useful PHP Code Snippets to Collect" ? In this article, the author will continue to provide you with 15 super useful jQuery code snippets.

jQuery provides many methods for creating interactive websites. When developing web projects, developers should make good use of jQuery codes. They can not only bring various animations and special effects to the website, but also improve the user experience of the website.

Let’s enjoy the charm of jQuery code together.

1. Preload images

(function($) { 
 var cache = []; 
 // Arguments are image paths relative to the current page. 
 $.preLoadImages = function() { 
  var args_len = arguments.length; 
  for (var i = args_len; i--;) { 
   var cacheImage = document.createElement('img'); 
   cacheImage.src = arguments[i]; 
   cache.push(cacheImage); 
  } 
 } 
jQuery.preLoadImages("image1.gif", "/path/to/image2.png"); 

2. Make every element on the page suitable for display on mobile devices

var scr = document.createElement('script'); 
scr.setAttribute('src', 'https://ajax.googleapis.com/ajax/libs/jquery/1.5.2/jquery.min.js'); 
document.body.appendChild(scr); 
scr.onload = function(){ 
  $('div').attr('class', '').attr('id', '').css({ 
    'margin' : 0, 
    'padding' : 0, 
    'width': '100%', 
    'clear':'both' 
  }); 
}; 

3. Image scaling

$(window).bind("load", function() { 
  // IMAGE RESIZE 
  $('#product_cat_list img').each(function() { 
    var maxWidth = 120; 
    var maxHeight = 120; 
    var ratio = 0; 
    var width = $(this).width(); 
    var height = $(this).height(); 
    if(width > maxWidth){ 
      ratio = maxWidth / width; 
      $(this).css("width", maxWidth); 
      $(this).css("height", height * ratio); 
      height = height * ratio; 
    } 
    var width = $(this).width(); 
    var height = $(this).height(); 
    if(height > maxHeight){ 
      ratio = maxHeight / height; 
      $(this).css("height", maxHeight); 
      $(this).css("width", width * ratio); 
      width = width * ratio; 
    } 
  }); 
  //$("#contentpage img").show(); 
  // IMAGE RESIZE 
}); 

4. Return to the top of the page

// Back To Top 
$(document).ready(function(){  
 $('.top').click(function() {  
   $(document).scrollTo(0,500);  
 }); 
});  
//Create a link defined with the class .top 
<a href="#" class="top">Back To Top</a> 

5. Use jQuery to create an accordion-style folding effect

var accordion = { 
   init: function(){ 
      var $container = $('#accordion'); 
      $container.find('li:not(:first) .details').hide(); 
      $container.find('li:first').addClass('active'); 
      $container.on('click','li a',function(e){ 
         e.preventDefault(); 
         var $this = $(this).parents('li'); 
         if($this.hasClass('active')){ 
             if($('.details').is(':visible')) { 
                $this.find('.details').slideUp(); 
             } else { 
                $this.find('.details').slideDown(); 
             } 
         } else { 
             $container.find('li.active .details').slideUp(); 
             $container.find('li').removeClass('active'); 
             $this.addClass('active'); 
             $this.find('.details').slideDown(); 
         } 
      }); 
   } 
}; 

6. Mimic Facebook’s image display method by preloading the previous and next images in the image gallery

var nextimage = "/images/some-image.jpg"; 
$(document).ready(function(){ 
window.setTimeout(function(){ 
var img = $("").attr("src", nextimage).load(function(){ 
//all done 
}); 
}, 100); 
}); 

7. Use jQuery and Ajax to automatically fill the selection box

$(function(){ 
$("select#ctlJob").change(function(){ 
$.getJSON("/select.php",{id: $(this).val(), ajax: 'true'}, function(j){ 
var options = ''; 
for (var i = 0; i < j.length; i++) { 
options += ' 
' + j[i].optionDisplay + ' 
'; 
} 
$("select#ctlPerson").html(options); 
}) 
}) 
}) 

8. Automatically replace lost pictures

// Safe Snippet 
$("img").error(function () { 
  $(this).unbind("error").attr("src", "missing_image.gif"); 
}); 
// Persistent Snipper 
$("img").error(function () { 
  $(this).attr("src", "missing_image.gif"); 
}); 

9. Show fade-in/fade-out effects on mouse hover

$(document).ready(function(){ 
  $(".thumbs img").fadeTo("slow", 0.6); // This sets the opacity of the thumbs to fade down to 60% when the page loads 
  $(".thumbs img").hover(function(){ 
    $(this).fadeTo("slow", 1.0); // This should set the opacity to 100% on hover 
  },function(){ 
    $(this).fadeTo("slow", 0.6); // This should set the opacity back to 60% on mouseout 
  }); 
}); 

10. Clear form data

function clearForm(form) { 
 // iterate over all of the inputs for the form 
 // element that was passed in 
 $(':input', form).each(function() { 
  var type = this.type; 
  var tag = this.tagName.toLowerCase(); // normalize case 
  // it's ok to reset the value attr of text inputs, 
  // password inputs, and textareas 
  if (type == 'text' || type == 'password' || tag == 'textarea') 
   this.value = ""; 
  // checkboxes and radios need to have their checked state cleared 
  // but should *not* have their 'value' changed 
  else if (type == 'checkbox' || type == 'radio') 
   this.checked = false; 
  // select elements need to have their 'selectedIndex' property set to -1 
  // (this works for both single and multiple select elements) 
  else if (tag == 'select') 
   this.selectedIndex = -1; 
 }); 
}; 

11. Prevent multiple submissions of forms

$(document).ready(function() { 
 $('form').submit(function() { 
  if(typeof jQuery.data(this, "disabledOnSubmit") == 'undefined') { 
   jQuery.data(this, "disabledOnSubmit", { submited: true }); 
   $('input[type=submit], input[type=button]', this).each(function() { 
    $(this).attr("disabled", "disabled"); 
   }); 
   return true; 
  } 
  else 
  { 
   return false; 
  } 
 }); 
}); 

12. Dynamically add form elements

//change event on password1 field to prompt new input 
$('#password1').change(function() { 
    //dynamically create new input and insert after password1 
    $("#password1").append(""); 
});

13. Make the entire Div clickable

blah blah blah. link 
The following lines of jQuery will make the entire div clickable: $(".myBox").click(function(){ window.location=$(this).find("a").attr("href"); return false; });  

14. Balance height or Div element

var maxHeight = 0; 
$("div").each(function(){ 
  if ($(this).height() > maxHeight) { maxHeight = $(this).height(); } 
}); 
$("div").height(maxHeight); 

15. Automatically load content when the window scrolls

var loading = false; 
$(window).scroll(function(){ 
  if((($(window).scrollTop()+$(window).height())+250)>=$(document).height()){ 
    if(loading == false){ 
      loading = true; 
      $('#loadingbar').css("display","block"); 
      $.get("load.php?start="+$('#loaded_max').val(), function(loaded){ 
        $('body').append(loaded); 
        $('#loaded_max').val(parseInt($('#loaded_max').val())+50); 
        $('#loadingbar').css("display","none"); 
        loading = false; 
      }); 
    } 
  } 
}); 
$(document).ready(function() { 
  $('#loaded_max').val(50); 
}); 

The 15 very practical jQuery code snippets collected in this article can be copied and pasted directly into the code, but developers are advised to understand the code before using it.