Best way to retrieve parameters from associative array in javascript?

Question

Within a function, I want to grab a set of parameters from a named array. What is the most efficient way of testing if the parameter exists in the array, and if it does, use it as a variable? I came up with a few alternatives.

target = $('#page_links')
if ( functionobject.target ) {
    target = functionobject.target
}

//method 2:
var target = ''
if ( functionobject.target ) {
    target = functionobject.target 
}
else {
    target = final_array
}

//method 3:
target = functionobject.target
if (typeof target == 'undefined') {
    target = $('#page_links')
}

Answer 1

I would say

var target = functionobject.target || $('#page_links');

How did I arrive at that? The important point to get across is that no matter what happens, you want to assign something to target. One first attempt to express that would be to use the ternary operator

var target = functionobject.target ? functionobject.target : $('#page_links');

However, the repetition of functionobject.target is ugly. It would be better to use the short-circuit evaluation feature of the a || b operator. If a is true, then evaluation stops, and the value of the expression is just a. Otherwise, the value of the expression is b.