setTimeout only sees last value in array? [duplicate]

问题

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Closed 8 years ago.

Possible Duplicate:
Javascript closure inside loops - simple practical example
How do I pass the value (not the reference) of a JS variable to a function?
Why always the last reference to the object is used in loop?

I have an array of ids which I loop over and want to use in a function called by setTimeout, however when "func" below is executed it only seems to see the last id stored in the array. I have been trying to uses closures to fix the issue but have had no success.

  // loop over array an call setTimeout for loading an image
  for (var i = 0; i < idlist.length; i++) {
    // variable i want use in function
    var lookup = idlist[i];

    var func = function() {
        alert(lookup); // this is always the last value in the "idlist" array
    };

    setTimeout(func, 500);
}

来源：https://stackoverflow.com/questions/7399411/settimeout-only-sees-last-value-in-array