Java 循环脚本

Question

我希望循环运行直到提示的值，但它会无限循环。需要帮忙。这是我的 javascript 代码： My code

var round = prompt("enter text");
var roundno = round;

var images_arr = ["../img/paper.png", "../img/stone.png", "../img/sisor.png"];
var size = images_arr.length
function myFunction() {
for (var i = 0; i = roundno; i + 1) {
    console.log(i);
    setInterval(function () {
        var x = Math.floor(size * Math.random())
        $('#random').attr('src', images_arr[x]);
    }, 1500);

    setInterval(function () {
        var sound = new Audio("../audio/audio.mp3");
        sound.play();
    }, 3000);

    if (i = roundno) {
        break;
     }
    }
  }

Answer 1

你没有递增i

改变

i + 1

以下之一：

i++
i += 1
i = i + 1

您还需要修复循环末尾的 if 语句。您要检查 i 是否等于 roundno。不要使用将 roundno 的值赋给 i 的赋值运算符 =，而是使用 == 或 === 进行相等性检查。

if (i == roundno) {
   break;
}

你在循环条件中也犯了同样的错字。将循环条件更改为 i == roundno 并删除循环末尾的 if 语句，因为在固定循环条件的情况下，循环内的 if 语句是不必要的。

for (var i = 0; i == roundno; i++) {
   // code
}

Answer 2

你的代码有很多问题。

var round = prompt("enter text"); // how do you know the user enters a number?
var defaultNumberOfRounds = 1;  // I added this row

// CHANGED THIS IN EDIT 
var roundno = round; // should be: isNaN(Number(round)) ? defaultNumberOfRounds : round

var images_arr = ["../img/paper.png", "../img/stone.png", "../img/sisor.png"];
var size = images_arr.length
function myFunction() {

// CHANGED THIS IN EDIT the conditions within () should be: var i = 0; i < roundno; i++
for (var i = 0; i = roundno; i + 1) {
    console.log(i);

    // all iterations in the loop will execute this at the same time.
    setInterval(function () {
        var x = Math.floor(size * Math.random())
        $('#random').attr('src', images_arr[x]); // JQuery
    }, 1500);

    // all iterations in the loop will execute this at the same time.
    setInterval(function () {
        var sound = new Audio("../audio/audio.mp3");
        sound.play();
    }, 3000);

    if (i = roundno) { // should be i == roundno
        break; // don't need to break it, because your for loop's condition should take care of this
     }
    }
  }
} // ADDED THIS IN EDIT: missing curly bracket

[edit] 我添加了一个片段来表明我的代码正在运行。我注释了 for 循环中的所有代码，我不得不更改声明 roundno 和 for 循环中的语句。

var round = prompt("enter text");
var defaultNumberOfRounds = 1;
var roundno = isNaN(Number(round)) ? defaultNumberOfRounds : round;
var images_arr = ["../img/paper.png", "../img/stone.png", "../img/sisor.png"];
var size = images_arr.length;
console.log(`round: ${round}, roundno: ${roundno}`);
function myFunction() {
  for (var i = 0; i < roundno; i++) {
    console.log(i);

    /*setInterval(function () {
        var x = Math.floor(size * Math.random())
        $('#random').attr('src', images_arr[x]); // JQuery
    }, 1500);

    setInterval(function () {
        var sound = new Audio("../audio/audio.mp3");
        sound.play();
    }, 3000);*/

  }
}

myFunction();

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