Annyce Davis

Davis Technology Consulting

jQuery each function

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jQuery has done it again with a very succinct function to iterate over the values of a set and perform an action for each one. The each function is easy to use and keeps your code from being cluttered with many for loops.


var allAlts = new Array();
$('img').each(function(){
allAlts.push(this.alt);
});

These few lines of code will get the alt attribute of every image tag in your document and store it in an array.

Passing HashMap as POST parameter

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If you would like to pass a hashmap as a parameter to a POST call in JavaScript, you need to use the dot notation and it will be interpreted as belonging to a hashmap. The code below loops through the properties of an object called ‘options’ and adds each one except for the toString() method to the POST parameter hashmap.

===================================================
Declaration of options variable

var options = {
 foo: 'blah',
 boo: 'muah',
  toString: function() {
   return this.foo + ', ' + this.boo;
 }
};

===================================================
Inside AJAX call function

if (options != null) {
for (property in options) {
   if (property != 'toString')
     post_data['options.' + property] = options[property];
}
}

Using this code when you access the POST parameters on the server side, you can reference the ‘options’ POST parameter as a hashmap, i.e. options[‘foo’].

Javascript Object declared within another Object

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In order to declare a Javascript object inside another one you would need to enter code similar to what is below.


var book = {
title: 'Nothing new!',
author: {name: 'Annyce', email:'annyce@gmail.com'}
};

You could then reference the author’s name via:
book.author.name

and if you wanted to update the name of the author, you would use
book.author.name = ‘Sarah’;

This feature of Javascript becomes very useful when you attempt to create an object with default settings and so forth.

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