for语句中的变量作用域问题，下列例子不太理解

Question

var myArr = [ 2, 3, 4, 5, 6];

var total = 0;

// Only change code below this line

for(var i = 0; i < myArr.length ; i++) {

  total += myArr[i];

}  //20

var myArr = [ 2, 3, 4, 5, 6];

// Only change code below this line

for(var i = 0; i < myArr.length ; i++) {

  var total = 0;

  total += myArr[i];

}  //6

Answer 1

上述都是var定义的方式，没有块级作用域的效果，两种结果不同的原因是因为第二中方式，每次初始化为零,效果等价于下面这种方式。var myArr = [ 2, 3, 4, 5, 6];// Only change code below this linevar&nbsp; total；for(var i = 0; i < myArr.length ; i++) {&nbsp; total = 0;&nbsp; total += myArr[i];}&nbsp; //6