How to determine if the checkbox is all selected in jquery

Judgment steps: 1. Get all checkbox elements, the syntax "$("input[type='checkbox']")" will return a jQuery object; 2. Select all selected elements, the syntax "$ (":checked")" will return a JQ object; 3. Calculate the length of the two objects and determine whether the two lengths are equal. The syntax is "checkbox element object.length==selected element object.length". If they are equal, then Select all, otherwise, not all are selected.

The operating environment of this tutorial: windows7 system, jquery3.6.1 version, Dell G3 computer.

Jquery method to determine whether the checkbox is all selected: Check whether the number of multi-selected elements in the checkbox is equal to the number of selected elements.

Implementation steps:

Step 1: Use the attribute value selector to obtain the checkbox element

$("input[type='checkbox']")

will be returned A jQuery object containing all checkbox elements.

Step 2: Use the :checked selector to select all selected elements

$(":checked")

will return a jQuery object containing all selected elements.

Step 3: Use the length attribute to calculate the length of the two jQuery objects and determine whether the two lengths are equal

checkbox元素对象.length==选中元素对象.length

• If equal (return If the value is true), then the checkbox is all selected

• If they are not equal (the return value is false), then the checkbox is not all selected

Implementation example: Determine whether the checkbox is all selected

         
         

          

           
          
         
         

          

           
          
         
         

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判断checkbox是否全选中

##Extended knowledge: attribute value selector

$("[attribute|='value']")

$(function(){ $('a[hreflang|="en"]').css("border","2px solid red"); //查找hreflang属性值是英语的所有链接。 });

$("[attribute*='value']")

attribute: an attribute name
value: an attribute value, which can be a word without quotes, or a quoted string.

$(function(){ $('input[name*="man"]').css("border","2px solid red"); //查找所有 input 的 name 属性中带有 'man' 的元素，并添加边框 });

$("[attribute~='value']")

attribute: an attribute name
value: an attribute value, which can be a word without quotes, or a quoted string.

$(function(){ $('input[name~="man"]').css("border","2px solid red"); //查找所有属性中含有 'man' 这个单词的文本框，并且修改其文本值。 })

$("[attribute$='value']")

attribute: an attribute name
value: an attribute value, which can be a word without quotes, or a quoted string.

$(function(){ $('input[name$="letter"]').css("border","2px solid red"); //查找所有的属性名称以"letter"的结束，并把他们的文字输入。 })

$("[attribute='value']")Selects elements whose specified attribute is the given value.
attribute: an attribute name.
value: An attribute value, which can be a word without quotes, or a quoted string.

$(function(){ $('input[value="Hot Fuzz"]').next().text("Hot Fuzz"); //查找input 中 value 值等于 Hot Fuzz 的将其后面的元素添加文本。 })

$("[attribute!='value']")Select the element whose specified attribute is not equal to this value
attribute: one Attribute name
value: An attribute value, which can be a word without quotation marks, or a quoted string.

$(function(){ $('input[name!="newsletter"]').next().append("；not newsletter") //查找input 中name 不等于 newletter 的下一个元素追加 文本。 注：主要含有这个字符串就行。 })

$("[attribute^='value']")Select the element that starts with the given string with the specified attribute.
attribute: an attribute name
value: an attribute value, which can be a word without quotation marks, or a quoted string.

$(function(){ $('input[name^="news"]').val("news here!"); //查找input 中 name 中含有new 这个字符串的 添加value 值。 })

$("[attribute]")Selects all elements with the specified attribute, which can be any value.
attribute: an attribute name.

$(function(){ $('div[id]').css("color","red") //给绑定id属性的div的文本颜色变成红色。 })

$("[attributeFilter1][attributeFilter2]attributeFilter3")## Select elements that match all specified attribute filters

attributeFilter2: Another attribute filter, used to further reduce the selected elements.
attributeFilterN: There are more attribute filters as needed.

$(function(){ $('input[id][name$="man"]').val('only this one') //查找那些有id属性，并且name 属性以man结尾的输入框，并设置值。 })

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