How do I tell Javascript to use zero as a variable if the passed variable if empty? In PHP I can use the following.
<?php
function test($var=0){
echo $var;
}
?>
So it would set $var to 0 if the passed variable was empty. I can't seem to figure this out in Javascript.
Thanks
If you call a method without providing a value for one (or more) of the arguments, those arguments will be undefined.
Thus within the method you can test whether the variable is defined, and if not assign it a default value:
function test(arg) {
if (typeof(arg) === 'undefined') {
arg = "default"; // or whatever default value you want
};
// Rest of method
}
It's not very elegant, but Javascript doesn't have a nice native default-arguments syntax.
var is a reserved keyword! your example will generate a syntax error.
You can use the or operator to do this a bit shorter;
function myFunc(var)
{
var = var || 0;
}
var is the boolean value false? Or an empty string? Or the integer 0? Or any other "truthy" value provided by the caller?It strongly depends on what empty means for you and what values the argument is allowed to have.
An often used shortcut is
param = param || 0;
This will set param to 0 whenever param evaluates to false.
This should work:
function myFunc(var) {
if (null == var)
var = 0;
}
var is not null if it's unprovided, it's undefined. Your code here would assign the default value even if the caller passed in an explicit value of null, which is not as I understand the requirement.