为什么设置超时内的curr值固定为3

Question

＆＃13;

＆＃13;

function printFruits(fruits) {

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

    var curr = i;

    console.log(curr);

    setTimeout(function() {

      console.log(curr);

      console.log(fruits[curr]);

    }, i * 1000);

  }

}

printFruits(["Lemon", "Orange", "Mango", "Banana"]);

＆＃13;

＆＃13;

＆＃13;

Answer 1

curr的值将是调用时的值，到那时curr的值已经达到 3 。

您需要锁定函数中的值。

(function(curr){setTimeout(function() {
  //console.log(curr);
  console.log(fruits[curr]);
}, i * 1000)})(curr);

<强>演示

function printFruits(fruits) 
{
  for (var i = 0; i < fruits.length; i++) 
  {
    var curr = i;
    //console.log(curr);
    (function(curr){setTimeout(function() {
      //console.log(curr);
      console.log(fruits[curr]);
    }, i * 1000)})(curr);
  }
}

printFruits(["Lemon", "Orange", "Mango", "Banana"]);