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What would be the best way to find all the possible related values with a group.
var table = [
{group:"a", stuff:"new"},
{group:"a", stuff:"old"},
{group:"b", stuff:"newOld"},
{group:"b", stuff:"old"},
{group:"c", stuff:"new"},
{group:"c", stuff:"old"},
{group:"c", stuff:"newOld"},
];
I want populate a Dropdown containing Unique group values. and on selection I want to use all related stuff for further processing. and also want to add a group which contains all stuff. for example
on selection of all -> new, old, newOld
a -> new, old
b -> newOld, old
c -> new, old, newOld
238
short and precise, without the overhead of looking up the entry each time in the whole array:
var groups = {all:{}};
table.forEach(function(a){
if (!groups[a.group]){ groups[a.group] = {}; }
groups[a.group][a.stuff] = groups["all"][a.stuff] = 1;
});
List the stuff in an object, thus you have no duplicate entries (that's why the rather redundant =1). But you could easily extend it to count the duplicates:
table.forEach(function(a){
if (!groups[a.group]){ groups[a.group] = {}; }
var stuff = groups["all"][a.stuff];
groups["all"][a.stuff] = !stuff ? 1 : ++stuff;
stuff = groups[a.group][a.stuff];
groups[a.group][a.stuff] = !stuff ? 1 : ++stuff;
});
The result will look like the following:
// "groups" holds all group elements and their stuff values
groups = { "all": {"new":2,"old":3,"newOld":2},
"a" : {"new":1,"old":1},
"b" : {"newOld":1,"old":1},
"c" : {"new":1,"old":1,"newOld":1}
}
To retrieve the values of a group, simply say:
var groupname = "a"; // whatever group you need
Object.keys(groups[groupname]);
// will give you:
["new","old"]
Demo
Gotta watch out for support of Object.keys and Array.prototype.forEach of course.
105
SOLUTION:
Using grep, map and unique (the usage of unique can be removed if "All" isn't needed). Here's the code :
function getOptions(value) {
//check if value sent in is an option or "All" options
var isAll = value === "All" ? true : false;
var forVal;
//If its "All" options
if (isAll) {
//yes, "All" has been chosen. yay!
//retreive all the values in "stuff" keys in array
var internal = $.map(table, function (r) {
return r["stuff"];
})
console.log(internal);
//get the unique values in internal[]
forVal = $.unique(internal);
//or use grep instead if u like to use unique with only DOM elements
} else {
//use grep to filter out the other options except the chosen option
var internal = $.grep(table, function (row) {
return row["group"] === value;
});
//rip out the the values in "stuff" keys in internal[]
forVal = $.map(internal, function (r) {
return r["stuff"]
});
}
//return the output variable
return forVal;
}
SCENARIO :
We've got a dropdown with these options - a, b, c, All.
<select id="questions">
<option>All</option>
<option>a</option>
<option>b</option>
<option>c</option>
</select>
When an option is chosen, you'd like to get the relevant output from getOption() and display it as another select.
$("select").change(function () {
//remove all #result select boxes - litter of previous option selection
$("#result").remove();
//get the options from the getOptions function
var source = getOptions(this.value);
//declare a select tag - will be inserted into <body> later
var $select = $("<select/>", {
"id": "result"
});
//construct an array of <option> tags
var $options = $.map(source, function (r) {
return $("<option/>", {
"html": r
});
});
//append $options to <Select> and then append $select to <body>
$select.append($options).appendTo("body");
});
DEMO http://jsfiddle.net/hungerpain/tSR5P/
EXTRA INFO ABOUT THE METHODS USED IN THIS SOLUTION
map
json object.unique
grep
Hope this helps!
44
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