javascript 如何从列表框中选择多个值

How to select multiple value from a listbox

提问by madhu

I have a below code where if I select one value, it works fine, but now I need such that when I select multiple values from the listbox, i have to get the value of selected values. How do i go about it? Here is the code,

我有一个下面的代码，如果我选择一个值，它工作正常，但现在我需要这样，当我从列表框中选择多个值时，我必须获取所选值的值。我该怎么做？这是代码，

HTML Code:

HTML代码：

<select id="attributeNames" name="attributeNames" size="5" multiple="multiple"         
onchange="getUniqueValues(value)">
<option value="Apple"> Apple </option>
<option value="Mango"> Mango </option>
<option value="Orange"> Orange </option>
<option value="Banana"> Banana </option>                                            
</select>

JavaScript:

JavaScript：

function getUniqueValues(value){
alert(value);
}

For instance: If I select Apple, then I get alert saying apple, now if I select apple & mango, I have to get the alert having apple & mango values. Facing problem here.

例如：如果我选择 Apple，那么我会收到警告说 Apple，现在如果我选择 apple & mango，我必须得到带有 apple & mango 值的警告。在这里遇到问题。

Here is the code: http://jsfiddle.net/5VtE3/2/

这是代码：http: //jsfiddle.net/5VtE3/2/

Thanks in advance,

提前致谢，

采纳答案by MD Sayem Ahmed

Here is an example on how to do it -

这是一个关于如何做到这一点的例子 -

HTML -

HTML -

<select id="attributeNames" name="attributeNames" size="5" multiple="multiple">
    <option value="Apple"> Apple </option>
    <option value="Mango"> Mango </option>
    <option value="Orange"> Orange </option>
    <option value="Banana"> Banana </option>                                            
</select>

? JS -

? JS -

window.onload = function () {
    var listbox = document.getElementById('attributeNames');
    listbox.onchange = function () {
        for(var index = 0; index < this.children.length; index++) {        
            if (this.children[index].selected) {
                console.log(this.children[index].value);
            }            
        }
    }?;
};

Live Demo.

现场演示。

回答by davneet

If you dont mind using jquery, -

如果您不介意使用 jquery，-

function getUniqueValues(){  
    var k=0;  
    var selected_list = {};  
    $('#attributeNames option').is(':selected').each(function(){  
        selected_list[k++] = $(this).val();  
        });  
    alert(selected_list);  
    }  

OR

或者

function getrUniqueValues(){  
    $('#attributeNames option').is(':selected').each(function(){  
        alert($(this).val());  
        });  
    }  

回答by nacx08

function getValue(id) {
                    var retval = "";
                    var lstdatabase = document.getElementById(id);
                    for (var i = 0; i < lstdatabase.options.length; i++) {
                        if (lstdatabase.options[i].selected) {
                            if (retval == "") {
                                retval = lstdatabase.options[i].value;
                            }
                            else {
                                retval = retval + ',' + lstdatabase.options[i].value;
                            }
                        }
                    }
                    return retval;
                }

回答by karaxuna

Try this:

试试这个：

<select id="attributeNames" onchange="getUniqueValues.call(this)" name="attributeNames" size="5" multiple="multiple">
    <option value="Apple"> Apple </option>
    <option value="Mango"> Mango </option>
    <option value="Orange"> Orange </option>
    <option value="Banana"> Banana </option>                                
</select>

function getUniqueValues(){
    for(var i = 0; i < this.options.length; i++){
        if(this.options[i].selected)
            alert(this.options[i].value);
    }
}

jsfiddle: http://jsfiddle.net/5VtE3/7/

jsfiddle：http: //jsfiddle.net/5VtE3/7/

回答by Slackware

You might want to try checkboxes

您可能想尝试复选框

<input type="checkbox" name="fruit" value="apple">Apple<br/>
<input type="checkbox" name="fruit" value="banana">Banana

Or you should just try to make:

或者你应该试着做：

<select id="attributeNames" name="attributeNames" size="5" multiple="multiple" onChange="getUniqueValues()" >
  <option value="Apple"> Apple </option>
  <option value="Mango"> Mango </option>
  <option value="Orange"> Orange </option>                                           
</select>

function getUniqueValues(){
var values = this;
}