常量作为JavaScript函数的输入吗？

Question

Say in my js file I want to have

var NO = 0;
var YES = 1;

function doYouLikeCake(answer){}

When doYouLikeCake is called from another file, I want to be able to input YES or NO, but I'm not sure how to do that if those variables are defined in the js file. Is this possible?

EDIT: Nevermind the HTML bit. No, there are no buttons. I'm trying to make a library, and want to simplify it so that the users of the library can just write doYouLikeCake(YES) rather than having to define YES/NO themselves.

Answer 1

Yes, you can do this:

<input type="submit" onclick="doYouLikeCake(YES);" value="Yes">
<input type="submit" onclick="doYouLikeCake(NO);" value="No">

<script>

    var NO = 0;
    var YES = 1;

    function doYouLikeCake(answer) { 
        //... 
    }

</script>

Answer 2

The boilerplate would be...

(function () {

    var YES = true;
    var NO = false;

    // All your JavaScript code here

}());

So, you want to put your "constants" inside your namespace, which can be achieved by an IIFE (like in my example above), or a DOM-ready handler. All your code should reside inside that namespace, which ensures that your "constants" are available to your code.

---

Btw, you can create real constants by creating non-writable properties:

Object.defineProperty( APP, 'YES', {
    value: true,
    enumerable: true
});

where APP is the namespace for the constant.

Answer 3

这是我上面的评论中的示例： http : //jsfiddle.net/vhQ8T/

Answer 4

If your variables are defined in the js file, you'll need to update the html element dynamically from the script.

For example this could be your html:

<input type="radio" name="YesOrNo" id="NO" value="PlaceHolderForNo" />NO
<input type="radio" name="YesOrNo" id="YES" value="PlaceHolderForYes" />YES

And your js:

var NO=0;
var YES=1;

var inputNO=document.getElementById("NO");
var inputYES=document.getElementById("YES");

// these are your variables

inputNO.value=NO; 
inputYES.value=YES;

inputNO.onclick=function(){doYouLikeCake(this.value);};
inputYES.onclick=function(){doYouLikeCake(this.value);};

The live example: http://jsfiddle.net/WhHXK/

Answer 5

Why do you need to input them. Just reference them since they are being declared in the global scope.

function doYouLikeCake()
{
    return YES;
}