[英]how to stop infinite loop when using callback inside while-loop in js
所以我正在創建一個像 Connect 4 這樣的游戲,它要求用戶輸入但我面臨的問題是我在 while 循環中使用了 callback(readline.question) function 每當我啟動代碼時它就開始無限循環而不詢問一個用戶的問題。 我怎樣才能暫停一段時間直到用戶回答? 我必須在不使用async/await的情況下解決這個問題。
function fetchColumn(player, callback) {
io.question(`Player ${player}, which Column? `, line => {
console.log(`You requested "${line}"`);
chosen_column = line;
callback();
});
}
let connect4 = new Connect4();
connect4.makeBoard(numRows, numCols, winLength);
while (game_over == 0) {
connect4.printBoard();
fetchColumn(current_player,()=>{
console.log(`you entered ${chosen_column}`);
if (chosen_column != 'Q' && chosen_column != 'q') {
move_status = connect4.place_piece(chosen_column, current_player);
x_in_a_row_status = connect4.x_in_a_row(current_player);
if (move_status == 0) {
// Further code-------
這就是我在終端中得到的。
Player 1, which Column?
A B C D E F G
. . . . . . .
. . . . . . .
. . . . . . .
. . . . . . .
. . . . . . .
. . . . . . .
Player 1, which Column?
A B C D E F G
. . . . . . .
. . . . . . .
. . . . . . .
. . . . . . .
. . . . . . .
. . . . . . .
----------Keep repeating----------
如果要在循環中調用異步 function,可以將while
與await
結合使用:
function fetchColumnAsync(player) {
return new Promise(function(resolve, reject) {
io.question(`Player ${player}, which Column? `, line => {
console.log(`You requested "${line}"`);
chosen_column = line;
resolve();
});
});
}
let connect4 = new Connect4();
connect4.makeBoard(numRows, numCols, winLength);
while (game_over == 0) {
connect4.printBoard();
await fetchColumnAsync(current_player);
console.log(`you entered ${chosen_column}`);
...
}
或遞歸結合回調 function:
function loop() {
if (game_over == 0) {
connect4.printBoard();
fetchColumn(current_player, () => {
console.log(`you entered ${chosen_column}`);
...
loop();
});
}
}
let connect4 = new Connect4();
connect4.makeBoard(numRows, numCols, winLength);
loop();
但是您不能將while
與回調結合使用,因為while
循環的第二次迭代同步開始,然后才能異步調用回調 function。 換句話說,它給出了一個無限循環。
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