javascript - Why did my incorrect if statement work? -

I recently came to the following syntax error:

  if (button == Of course this should be:  
  if (button == "init" | button = "init" "Show_selected"} "show_all") {  
 = "Show_selected" || button == "show_all") {  
 But, the original statement seemed to work perfectly in Chrome, FF and IE 9 !!? I was just concerned about my mistake when adding a new option.  
 To clarify, string logic is used when calling "in_select", "show_selected" and "show_all" function; E.g.  
  onclick = myFunction ("init");  
 
 I'm sure that I miss early while trying to get such a short story when learning JS and knowing very quickly that it does  no  work. 
 
 I have already corrected the code, but I am worried that I do not know why this was working. 
 
 Can someone shed light on this puzzle? 

Of course this will work, and it will always work because your status < Strong> always correct :

  if (button == "init" || "show_selected" || "show_all")  < / Pre> 
 will always look true because  "show_selected"  is a string and if you pass it as a statement statement it will always be true, your code will be evaluated this way 
 
  if (button == "init" || true || true) // will always be true  
 
 Because  Write ("show_all")  is equal to  ("show_all"! == zero)  which is  true . 
 
 For example, try: 
 
 
 
 
  if (" show_all ") {// return true (statement is true) alert (true); }