SOURCE

console 命令行工具 X clear 

                    

                        
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console

            
(function() {
    var jack = 'Jack';
})();
alert(typeof jack)

            
<p><b>Question:</b></p>
Why does it alert undefined when I declared the jack variable to be 'Jack'?
<p><b>題目:</b></p>
为什麽提示为"undefined"？