How can I get a list of all values in select box?

问题:

I am stumped. I have a form with a dropdown list, and I would like to grab a list of all the values in the list. I pulled the below example from w3 schools (yes, I know it's unreliable, but other solutions on stack overflow seem to be very similar to this). It was not working for me, and I tried plugging it into jsfiddle, but no luck.

HTML:
<form>Select your favorite fruit:
    <select id="mySelect">
        <option value="a">Apple</option>
        <option value="o">Orange</option>
        <option value="p">Pineapple</option>
        <option value="b">Banana</option>
    </select>
</form>
<button type="button" onclick="displayResult()">Display text of all options</button>

javascript:

function displayResult() {
    var x = document.getElementById("mySelect");
    var txt = "All options: ";
    var i;
    for (i = 0; i < x.length; i++) {
        txt = txt + "\n" + x.options[i].value;
    }
    alert(txt);
}

Not working on jsfiddle: http://jsfiddle.net/WfBRr/1/

However, it works at their site: http://www.w3schools.com/jsref/tryit.asp?filename=tryjsref_option_text2

Any ideas on how to solve this?

回答1:

You had two problems:

1) The order in which you included the HTML. Try changing the dropdown from "onLoad" to "no wrap - head" in the JavaScript settings of your fiddle.

2) Your function prints the values. What you're actually after is the text

x.options[i].text; instead of x.options[i].value;

http://jsfiddle.net/WfBRr/5/

回答2:

Change:

x.length

to:

x.options.length

Link to fiddle

And I agree with Abraham - you might want to use text instead of value

Update
The reason your fiddle didn't work was because you chose the option: "onLoad" instead of: "No wrap - in "

回答3:

As per the DOM structure you can use below code:

var x = document.getElementById('mySelect');
     var txt = "";
     var val = "";
     for (var i = 0; i < x.length; i++) {
         txt +=x[i].text + ",";
         val +=x[i].value + ",";
      }

回答4:

It looks like placing the click event directly on the button is causing the problem. For some reason it can't find the function. Not sure why...

If you attach the event handler in the javascript, it does work however.

See it here: http://jsfiddle.net/WfBRr/7/

<button id="display-text" type="button">Display text of all options</button>

document.getElementById('display-text').onclick = function () {
    var x = document.getElementById("mySelect");
    var txt = "All options: ";
    var i;
    for (i = 0; i < x.length; i++) {
        txt = txt + "\n" + x.options[i].value;
    }
    alert(txt);
}