正向遍历-反向

const testArr =  [1,2,3,4,5,6,7,8,9,10]
// 反向遍历
for (let dynamicLength = testArr.length - 1; dynamicLength >= 0; dynamicLength--) {
  const element = testArr[dynamicLength];
  console.log('element:',element) 
  // if(element === 5){
  //   console.log('break:') 

  //   break
  // }
}


const testArr =  [1,2,3,4,5,6,7,8,9,10]
// 正向遍历
for (let index = 0; index < testArr.length; index++) {
  const element = testArr[index];
   console.log('element:',element) 
  if(element === 5){
    console.log('break:') 

    break
  } 
}