Set a default parameter value for a JavaScript function - Stack Overflow

There are a lot of ways, but this is my preferred method - it lets you pass in anything you want, including false or null. (typeof null == "object")

 function foo(a, b)   {     a = typeof a !== 'undefined' ? a : 42;     b = typeof b !== 'undefined' ? b : 'default_b';     ...   }

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