Unable to Use Javascript Variable

Question

I have a Javascript variable period being used in a function. I am unable to figure out how to use this same variable in other areas such as a document.write () function in part 2. I thought period was a global variable. What this entire page does, when I select a number in my list it hides the extra lines I don't need.

In part three, where I added var x = period, if I type document.write(period) it gives me the value I want. I just can't get that value anywhere else but that specific location. Basically, I need the report(this.value) value in my document.write() in part 2.

What I think is happening is report(this.value) doesn't report until a number is selected in my list so the HTML is written before I can use it. Not sure though.

I would really appreciate it if someone can help me with this. Thanks.

Also, Is there a better way to select a number in a list that I can use the variable anywhere. Thanks.

Part 1

<select size="1" id="Number" Name="Number1" onchange="report(this.value)">
    <option value="" selected>How Many</option>
    <option value="1">1</option><option value="2">2</option>
</select>

Part 2

<p id="1">
    &nbsp;
    <script>document.write (x,")");</script>
    Primary silkscreen layer
    <img src="../0_Images/blank.jpg" width="60" height="15">
    File name: &nbsp;
    <input name="Primary Silkscreen12" type="text" size="60" style="border:3px solid #1871D1;" />
</p>

Part 3

function report(period) {
    var x = period
    if (period=="1") {
        var i = 1;
        do {
            + i;
            i++;
            var e = document.getElementById(i);
            e.style.display = 'none'
        } while (i < 34)
    }
}

The document.write(x,")"); has no knowledge of the x in the report function. You will have to append x's value to the DOM from within the report function. — 76484
– 76484, Commented Aug 9, 2014 at 18:04

tvkanters · Accepted Answer · 2014-08-09 17:12:29Z

1

Basically, var defines the local function scope as the one that the variable is available in. Simply initiating a variable without the var keyword will make it available in the global scope as per the default behaviour.

You can either save those types of variables in the global scope or, if you like ordering stuff neatly, use a function as an improvised class to store certain variables in. Alternatively, you can simply query the value from the select each time you need it and it won't need JS storing at all. It depends on your full implementation which option is most suitable.

answered Aug 9, 2014 at 17:12

tvkanters

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3 Comments

JohnB Over a year ago

"Querying the value from the select" sound like what I need. I am not sure how to do that. I've been working with javascript on and off for only a short time.

tvkanters Over a year ago

You can get the selected value with something like selectbox = document.getElementById("Number"); selectedvalue = selectbox.options[selectbox.selectedIndex].value. I would advise putting it in a function if you use it often.

JohnB Over a year ago

I have found that I am taking information from the textbox before I need it which is why it is blank. I am attempting to put x = document.getElementById("Number").value; into my function. I have also replaced Part 1 with <input id="Number" name="Number" type="text" size="10" maxlength="5" value="test" onfocusout="report(this.value)">

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