JS: Change select option value on being selected with prompt? - javascript

I've looked around and I don't see this being asked before.
I have a select box, like so:
<select onchange="change()">
<option value="" selected>Option 1</option>
<option value="30">Option 2</option>
<option value="90">Option 3</option>
</select>
I want to add another option...
<option value="custom">Option 4</option>
...that when chosen (clicked) an alert box will popup asking the user to type in a number (in the case 30 or 90 weren't viable options, as in the values of the option's) to replace the value of the option.
<script>
function change() {
if(value == "custom") {
value = prompt("Please enter a new number:", "60");
}
}
</script>
I wanted to know what the best way to do this is with plain old javascript - I'll use jQuery if I have to.
Any ideas? An example would be great as well.

Take a look at this code. I think this is what you're trying to do:
HTML
<select id="optionvals" onclick="change()">
<option value="" selected>Option 1</option>
<option value="30">Option 2</option>
<option value="90">Option 3</option>
<option value="custom">Option 4</option>
</select>
JS
function change() {
var oItem = document.getElementById('optionvals');
var value = oItem.options[oItem.selectedIndex].value;
if(value == "custom") {
alert("you've clicked b");
value = prompt("Please enter a new number:", "60");
oItem.options[oItem.selectedIndex].value = value;
console.log(oItem.options[oItem.selectedIndex].value)
}
}
What this does is prompt you on the change only if the selected value in the options is custom. Then after you choose a custom value, it will rewrite the value of that the custom option element to the value you just entered in the prompt. I logged the new value after assigning it to show you that it is working.
Here is a fiddle: https://jsfiddle.net/ng7xvy05/

Your onchange event is the appropriate way to handle this. This is mostly a matter of user interface (UX) design though. To do this in the prompt fashion you ought to use parseFloat:
change() {
var value = prompt('You\'ve chosen Other. Please enter a value', '60');
if(value) {
value = parseFloat(value);
// apply it to your model
} else {
// apply NULL to your model
}
}
From a UXD point of view I would use a typeahead input. It would autosearch known answers but also allow the user to input their own. This is not standard html so you would need to write this yourself or use jquery. But from a user interface design point of view, prompts suck.

Related

make a select dependent with js

I would like to do a select option dependent of another select, i saw there's a way using array with fixed values, but my array is reloaded every time we add a new form field on the form. I would like something like when i select op1, then it just show op1 options on second select.
<select id="id1" name="optionshere">
<option relone="op1">opt one</option>
<option relone="op2">opt two</option>
</select>
<select id="id2" name="resulthere">
<option relone="op1">ans 1 op1</option>
<option relone="op1">ans 2 op2</option>
<option relone="op2">ans 1 op2</option>
</select>
Any idea?
thanks all
Here's a method without jQuery:
When you select an option in the first selectbox, it will hide everything that doesn't match its relone.
var id1 = document.getElementById("id1");
var id2 = document.getElementById("id2");
id1.addEventListener("change", change);
function change() {
for (var i = 0; i < id2.options.length; i++)
id2.options[i].style.display = id2.options[i].getAttribute("relone") == id1.options[id1.selectedIndex].getAttribute("relone") ? "block" : "none";
id2.value = "";
}
change();
<select id="id1" name="optionshere">
<option relone="op1">opt one</option>
<option relone="op2">opt two</option>
</select>
<select id="id2" name="resulthere">
<option relone="op1">ans 1 op1</option>
<option relone="op1">ans 2 op1</option>
<option relone="op2">ans 1 op2</option>
</select>
If Jquery is an option you may go with something like this:
<script type='text/javascript'>
$(function() {
$('#id1').change(function() {
var x = $(this).val();
$('option[relone!=x]').each(function() {
$(this).hide();
});
$('option[relone=x]').each(function() {
$(this).show();
});
});
});
</script>
Then to expand:
There really are many ways in which you can solve this predicament, depending on how variable your pool of answers is going to be.
If you're only interested in using vanilla javascript then let's start with the basics. You're going to want to look into the "onchange" event for your html, so as such:
<select onchange="myFunction()">
Coming right out of the w3schools website, on the Html onchange event attribute:
The onchange attribute fires the moment when the value of the element
is changed.
This will allow you to make a decision based on this element's value. Then inside your js may branch out from here:
You may use Ajax and pass to it that value as a get variable to obtain those options from a separate file.
You may get all options from the second div through a combination of .getElementbyId("id2") and .getElementsByTagName("option") then check for their individual "relone" attribute inside an each loop, and hide those that don't match, and show those that do.
Really, it's all up to what you want to do from there, but I personally would just go for the Jquery approach

Javascript Div onchange Grab Values from Two Select Boxes

I'm trying to make it so when a select box within a div changes, it will grab values from both that select box and one other one that I've yet to add, but I don't know how to go about it.
I currently have this code
<select id='selMag' onchange='getSelMag(this)'>
<option value='0.0>Select Minimum Magnitude</option>
<option value='1.0'>1.0</option>
<option value='2.0'>2.0</option>
<option value='3.0'>3.0</option>
<option value='4.0'>4.0</option>
<option value='5.0'>5.0</option>
<option value='6.0'>6.0</option>
<option value='7.0'>7.0</option>
<option value='8.0'>8.0</option>
<option value='9.0'>9.0</option>
<option value='10.0'>10.0</option>
</select>
function getSelMag(sel) {
value = Number(sel.value);
console.log(window.value);
}
This, as it is right now, works fine from grabbing it from the , but I would like to add another one and put them inside a container div, and make it so when either one changes it will grab the values from both of them, add both strings together, and convert them into a number. I plan to make it so the select box above will not have the decimal values and just be 1, 2, etc. and have the second box be .1, .2, etc. so when they are added together, it will show 1.1, 1.2, etc.
Presumably, the select is in a form. To be successful, form controls must have a name, so:
<select id='selMag' name='selMag' onchange='getSelMag(this)'>
Adding a name nearly always obviates the requirement for an ID. If the other select also has a name:
<select name='selMag2'>
and it belongs to the same form as the first, you can reference it from the getSelMag function via the form:
function getSelMag(sel) {
// Always declare variables
var value = Number(sel.value);
// Access them from the appropriate scope
console.log(value);
// Reference the other select using named properties of the form
var otherSelect = sel.form.selMag2;
// Do stuff with it
var otherValue = otherSelect.value;
}
Note that all form controls have a form property that references their parent form, and that the controls belonging to a form can be accessed via the form's elements collection.
Those with names (and in some browsers those with IDs) can be accessed as named properties of the form and of the elements collection, and also by index in the collection.
It seems that you want to concatenate the values with a period between, so the function might look like:
function getSelMag(sel) {
var value0 = sel.form.selMag.value;
var value1 = sel.form.selMag2.value;
console.log(value0 + '.' + value1);
}
and the HTML:
<form>
<select name="selMag" onchange="getSelMag(this);">
<option value="0" selected>0
<option value="1">1
<option value="2">2
</select>
<select name="selMag2" onchange="getSelMag(this);">
<option value="0" selected>0
<option value="1">1
<option value="2">2
</select>
</form>
Use the answer from this link to get the value of other select box in getSelMag() function
Get selected value in dropdown list using JavaScript?
as follows:
function getSelMag(sel) {
value = Number(sel.value);
console.log(window.value);
var e = document.getElementById("selMag2");
var option2 = e.options[e.selectedIndex].text;
//do whatever u want
}
You can make another function say x() that will be called for other select box you make and access the value of first select box from that
<select id='selMag2' onchange='x(this)'>
as
function getSelMag2(sel) {
value = Number(sel.value);
console.log(window.value);
var e = document.getElementById("selMag");
var option1 = e.options[e.selectedIndex].text;
//do whatever u want
}
Hope this helps

jQuery - Set the selected option of a select box using value or text with options nested in optgroups

So I am writing an app that requires an address input and I have a select element for the user to select the state/province. It needs to support the US and Canada so it has nested optgroups to separate those out and a single, first level option as it's default value. Here is a basic example:
<select name="state" id="state">
<option class="co" value="" data-placeholder="true" disabled selected>Choose your state...</option>
<optgroup label="United States">
<option class="co" value="AL">Alabama</option>
<option class="co" value="AK">Alaska</option>
<option class="co" value="AZ">Arizona</option>
</optgroup>
<optgroup label="Canada">
<option class="co" value="AB">Alberta</option>
<option class="co" value="BC">British Columbia</option>
<option class="co" value="MB">Manitoba</option>
</optgroup>
Now I need to programmatically select the option that matches input from an external source and I want to check for a match based on both the value of the option element or its text. Whichever option is a match would then be set as the selected option. I know you can set the selected option by value using
$("#state").val(myValue)
and I know you can set an option based on text in this way
var myText = "The state I want.";
$("#state").children().filter(function() {
return $(this).text() == myText;
}).prop('selected', true);
Is there a clean way to do this without having to run through each child and checking if it's an optgroup and then running through all its children to check for a match? Is there an easy way through jQuery to combine the value and text methods of setting the selected option?
One other complication, I am going to be doing this within an external jQuery plugin. Within the function I need to modify I have the select element as a variable
$element
so I need a way to do it kind of like this if possible:
$element.descendents(":option").filter(function() {
//do the selecting here
}).prop('selected', true);
If you want to select by the option value, use the value selector:
var myText = "AZ";
$('#state option[value="' + myText + '"]').prop('selected', true);
If you want to search by the option's label, use a filter:
var myText = "Arizona";
$('#state option').filter(function () { return $(this).html() == myText; }).prop('selected', true)
Solved. Since I already had my element passed to a function as a jQuery variable, $element, I couldn't just use the standard selector in the form of:
$("#state option").filter(
// filter function
).prop('selected', true);
After a lot of trying, I got this and it works:
function functionIHadToChange($element, value) {
// other code
$element.find("option").filter(function(){
return ( ($(this).val() == value) || ($(this).text() == value) )
}).prop('selected', true);
}
I am not sure I understood completely your question but I am attempting to answer it in this fiddle
The trick being that you can select it by setting the value of the select box directly
$("#state").val( a_value );
You can set it by $("#select_id").prop("selectedIndex", 3); // Select index starts from zero.
Read here for example this.
$element = $('select#state');
$options = $element.find('option');
$wanted_element = $options.filter(function () {
return $(this).val() == "Alabama" || $(this).text() == "Alabama"
});
$wanted_element.prop('selected', true);
Would be one way to do it.
But i would guess, without knowing the exact internas of the .find() method, in the end jQuery will use at least two loops itself to perform this...
I'm late here but for future visitor, easiest way to do that is :
html
<select name="dept">
<option value="">This doctor belongs to which department?</option>
<option value="1">Orthopaedics</option>
<option value="2">Pathology</option>
<option value="3">ENT</option>
</select>
jQuery
$('select[name="dept"]').val('3');
Output: This will active ENT.

jquery not getting value from select statement on change

This is really odd, but I am probably missing something simple. I have a simple select statement where a user can choose a value.
onChange calls a function getDrop2() which currently I am trying to get it to alert me which option is chosen.
my html is:
<select onChange= "getDrop2()" id = "drop1" >
<option value="0">All</option>
<option value="1">Alphabetical</option>
<option value="2">Brewery</option>
<option value="3">Style</option>
</select>
My Javascript is:
function getDrop2(){
var choice = $("#drop1").val()
alert(choice);
}
The output of the alert statement is just blank.
In jQuery, you're better off doing something like:
<select id = "drop1" >
<option value="0">All</option>
<option value="1">Alphabetical</option>
<option value="2">Brewery</option>
<option value="3">Style</option>
</select>
With the following JavaScript:
$(function(){
$('#drop1').change(function() {
var choice = $(this).val();
alert(choice);
}
});
The idea is that jQuery is now attaching the change function automatically to the select with the id of "drop1" By using this pattern, you've decoupled the HTML from the JavaScript that's doing the business logic.
Although what others have selected is a better approach. My answer is just to tell you why your code is not working
Try this
var choice = $('#drop1 option:selected').val()
Instead of
var choice = $("#drop1").val()

HTML/JS: Validating value in <selected>-list

I'm really new to this and working on a JavaScript code and I want to see if a dropdownlist has any choosen value. How do i do that?
I tried:
var selectObj = form.document.getElementById('myListId');
var selectInd = selectObj.selectedInd;
and tried:
if(selectInd == "")
to check if it was empty.
What do I need to change to make it work?
Thanks in advance!
A drop-down, by design, always has a value selected. If you just want to leave an empty value first to not choose something for the user, you can simply check if it's value is empty.
document.getElementById("validate").onclick = function() {
if (document.getElementById("foo").value == "")
alert("invalid");
else
alert("valid");
};
Live example
According to comments, this might not work in older versions of IE. Be sure to test it there if you need to support those browsers.
HTML
<select id="myListId">
<option value="">- Select an option-</option>
<option value="1">Option 1</option>
<option value="2">Option 2</option>
<option value="3">Option 3</option>
</select>
Javascript
function checkvalue(){
var selectObj = form.document.getElementById('myListId');
if (selectObj.value != "") {/* DO something */}
}
Now you can execute this function on change of the select box, or when you submit the form, it is up to you.
Try to read this example.
You are trying compare a number (selectObj.selectedIndex) with a string (""), you should write something like this:
var selectObj = document.getElementById('myListId'),
selectInd = selectObj.selectedIndex,
selectedVal = selectObj.options[selectInd].value;
if(selectedVal== "") {
/* do your stuff*/
}
Only to notice: This only would work (detect a value equal to "") with an html like this:
<select id="myListId">
<option value="" selected="selected">Empty value</option>
<option value="1">Non empty value</option>
</select>
Or when the user has been selected the option "Empty value".
EDIT:
Try with this demo. This demo also works in IE7.

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