javascript 多维数组和关联数组

Question

i am new of javascript, i have been told by someone, he said "speak strictly, javascript doesn't have multidimensional Array and associative array ". but in a book, i saw the following

var my_cars=Array();
my_cars["cool"]="Mustang";

$a=Array(Array(0,1),2);

so the opinion form he is wrong? am i right?

Answer 1

JavaScript has arrays of whom their elements can be other arrays.

However, JavaScript has Object s with properties, not associative arrays.

Buy a better book .

1. [] is much better than Array() . Also, why not instantiate an Array object explicitly then rely on Array returning a new object?
2. The example is setting the property cool on the Array .
3. Why the $a sigil? Why no new operator again?

Answer 2

All the explanations of Javascript Multidimensional arrays seem to be very convoluted, after almost an hour of research I came across this simple example:

var myArray = new Array();
myArray['row1'] = { 'col1':'BLARGH!!!', 'col2':'HONK!!!!' }
myArray['row2'] = { 'col1':'FOO!!!', 'col2':'BAR!!!!' }
myArray['row3'] = { 'col1':'FOUR!!!', 'col2':'GREGS!!!' }

document.write(myArray['row2']['col1'] + " - " + myArray['row3']['col2']);
//will output: FOO!!! - GREGS!!

I found it here: http://moblog.bradleyit.com/2009/06/create-multidimensional-associative.html

Answer 3

The line: my_cars["cool"]="Mustang"; is actually not adding a value into the array. It is in fact adding a new property and value to the object my_cars . The following code would also work same:

var my_cars = new Function();
my_cars["cool"]="Mustang";
alert(my_cars["cool"]);

var c = new Object();
c["cool"]="Corvette";
alert(c["cool"]);

To understand how this works, you can check out my blog post on arrays and maps .

Btw, as @alex says, Buy A New Book.