为什么在获得以下代码的输出时 i 的值显示为 undefined

Question

 let i = 0; const g = (i, callback) => { if (i < 100) { callback(i) i++; g(i, callback) } else return } const k = (i) => { setTimeout((i) => { console.log('hi' + i); }, i * 1000); } g(i, k);

This is the code which uses callback to print hi concatenated by the value of i at an interval of 1 second for 100 times. i am not able to identify where it is going wrong .It will be very greatful if anyone could help me with this.

Answer 1

The i inside the function passed to setTimeout shadows the one k accepts as argument. So to correct a snippet you just need to remove callback's argument:

 let i = 0; const g = (i, callback) => { if (i < 100) { callback(i) i++; g(i, callback) } else return } const k = (i) => { setTimeout(() => { // <------ I removed `i` here console.log('hi' + i); }, i * 1000); } g(i, k);