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JavaScript Pass Variables Through Reference

How can you do something like this in javascript?

In PHP you can put a & in a function in front of the parameter to write directly back to the variable.. How can you do something like this in javascript?

Answer 1

In JavaScript, values are passed to functions by value. Objects, however, are passed by reference.

Passing values:

function myfunction(x)
{
      // x is equal to 4
      x = 5;
      // x is now equal to 5
}

var x = 4;
alert(x); // x is equal to 4
myfunction(x); 
alert(x); // x is still equal to 4

Passing objects:

function myobject()
{
    this.value = 5;
}
var o = new myobject();
alert(o.value); // o.value = 5
function objectchanger(fnc)
{
    fnc.value = 6;
}
objectchanger(o);
alert(o.value); // o.value is now equal to 6

Source: http://snook.ca/archives/javascript/javascript_pass