javascript - logOnce higher order function -

I want to implement a function that takes another function as argument, and a new version of that function Which can only be called once.

The first thing does, but the second does not work.

Why does another function not work, but anyhow a function like this one inside the first one?

  var logon = once (console.log) function once (fn) {var call = true; Return work (word) {if (call) {call = false; Return FN (word); }}} Function once (fn) {var call = true; If (call === true) {call = false; Return FN; }} Logon ("foo"); ---- & gt; "Foo" logon ("blue"); ---- & gt; "Blue"  
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 Your second method does not work because it's the same  fn . In fact, this is equivalent to 
 
  function (fn) {return fn; }  
 
 Therefore,  one time (console.log) is  just  console.log , and you can call it 
 
 The first approach works because you return a  different  function, which will be the original one or call on the basis of a value.