I have a HTML list of about 500 items and a "filter" box above it. I started by using jQuery to filter the list when I typed a letter (timing code added later): $('#filter').keyup( function() { var jqStart = (new Date).getTime(); var search = $(this).val().toLowerCase(); var $list = $('ul.ablist > li'); $list.each( function() { if ( $(this).text().toLowerCase().indexOf(search) === -1 ) $(this).hide(); else $(this).show(); } ); console.log('Time: ' + ((new Date).getTime() - jqStart)); } ); However, there was a couple of seconds delay after typing each letter (particularly the first letter). So I thought it may be slightly quicker if I used plain Javascript (I read recently that jQuery's each function is particularly slow). Here's my JS equivalent: document.getElementById('filter').addEventListener( 'keyup', function () { var jsStart = (new Date).getTime()...
with jquery you can call $.extend
ReplyDeleteobj1 = {a: 1, b: 2};
obj2 = {a: 4, c: 110};
obj3 = $.extend(obj1, obj2);
obj1 == obj3 == {a: 4, b: 2, c: 110}
(assoc. arrays are objects in js)
look here: http://api.jquery.com/jQuery.extend/
This is how Prototype does it:
ReplyDeleteObject.extend = function(destination, source) {
for (var property in source) {
if (source.hasOwnProperty(property)) {
destination[property] = source[property];
}
}
return destination;
};
called as, for example:
var arr1　= { robert: "bobby", john: "jack" };
var arr2 = { elizabeth: "liz", jennifer: "jen" };
var shortnames = Object.extend(arr1,arr2);
EDIT: added hasOwnProperty() check as correctly pointed out by bucabay in comments
In dojo, the 2-objects/arrays "merge" would be dojo.mixin(destination, source) -- you can also mix multiple sources into one destination, etc -- see the mixin function's reference for details.
ReplyDeleteIn Javascript there is no notion of
ReplyDeleteassociative array, there are objects
The only way to merge two objects is
to loop for their properties and
copy pointers to their values that
are not primitive types and values
for primitive types to another
instance
do you want to overwrite a property if the names are the same but the values are not?
ReplyDeleteAnd do you want to permanently change one of the original objects,
or do you want a new merged object returned?
function mergedObject(obj1, obj2, force){
for(var p in obj1) this[p]= obj1[p];
for(var p in obj2){
if(obj2.hasOwnProperty(p)){
if(force || this[p]=== undefined) this[p]= obj2[p];
else{
n= 2;
while(this[p+n]!== undefined)++n;
this[p+n]= obj2[p];
}
}
}
}
Underscore also has an extend method:
ReplyDeleteCopy all of the properties in the source objects over to the
destination object. It's in-order, so the last source will override
properties of the same name in previous arguments.
_.extend(destination, *sources)
_.extend({name : 'moe'}, {age : 50});
=> {name : 'moe', age : 50}
Yahoo UI (YUI) also has a helper function for this:
ReplyDeletehttp://developer.yahoo.com/yui/examples/yahoo/yahoo_merge.html
YAHOO.namespace('example');
YAHOO.example.set1 = { foo : "foo" };
YAHOO.example.set2 = { foo : "BAR", bar : "bar" };
YAHOO.example.set3 = { foo : "FOO", baz : "BAZ" };
var Ye = YAHOO.example;
var merged = YAHOO.lang.merge(Ye.set1, Ye.set2, Ye.set3);
Keep it simple...
ReplyDeletefunction mergeArray(array1,array2) {
for(item in array1) {
array2[item] = array1[item];
}
return array2;
}