Actionscript 3;錯誤1086

Question

目前在ActionScript3編碼遊戲，下面的函數不斷吐出這個錯誤;

function checkAnswer(e:KeyboardEvent):void{ 
    var input:String(this.userInput.text).toLowerCase(); 
    var currentLetter:int; 
    var currentWord = currentFruit; 
    while (currentLetter < input.length){ 
    if (this.currentWord.charAt(currentLetter) == input.charAt(currentLetter)){ 
        trace("correct"); 
       } else { 
        trace("incorrect"); 
       }; 
      currentLetter++; 
     } 

}; 

而且錯誤;

Scene 1, Layer 'Actions', Frame 1, Line 81 1086: Syntax error: expecting semicolon before leftparen. 

我不知道爲什麼它這樣做。有沒有人有任何線索？誰能幫忙？

Answer 1

變化

var input:String(this.userInput.text).toLowerCase(); 

到

var input:String = this.userInput.text.toLowerCase();