//未优化的代码，很慢
for(var i = 0; i < 1000; i++){
var my_variable = 'This is my variable';
// Do something with my_variable
}

//优化后的代码，快
var my_variable;
for(var i = 0; i < 1000; i++){
my_variable = 'This is my variable';
// Do something with my_variable
}
//javascript/2141