多次运行 Mathrandom

Question

I have a setTimeout function which prints a random number. However, when I run the snippet multiple times in a row in quick succession, the same random number is printed.

Where am I doing wrong?

Here is my function:

 function generateRandomNumber(min, max) { return Math.floor(Math.random() * (max - min + 1) + min); } var t = generateRandomNumber(5000, 10000); setTimeout(function() { console.log("RandomNumber" + " " + t); }, t);

Answer 1

You are seeing the same result when you run the snippet multiple times because the value of t is being changed every time but the value is not immediately printed . Thus, when the timeouts run after t milliseconds, t will have already been set to the last randomly generated value.

See the following, which demonstrates what is going on:

 function generateRandomNumber(min, max) { return Math.floor(Math.random() * (max - min + 1) + min); } var t; function test(){ t = generateRandomNumber(5000, 10000); console.log(`t set to ${t}`) setTimeout ( function () {console.log("RandomNumber"+" " + t);}, 1000 ); } test() test() test()

You can solve this by storing t privately, inside a function for instance:

 function generateRandomNumber(min, max) { return Math.floor(Math.random() * (max - min + 1) + min); } function test() { var t = generateRandomNumber(5000, 10000) setTimeout(function() { console.log("RandomNumber" + " " + t); }, t); } test() test() test()

---

To log one after the another with random times ( as requested ), you can call setTimeout recursively:

 function generateRandomNumber(min, max) { return Math.floor(Math.random() * (max - min + 1) + min); } const send = () => { const t = generateRandomNumber(100, 1000) setTimeout(() => { console.log("Message: " + t) send() }, t) } send()