Javascript 函数不起作用，控制台显示它未定义

Question

我有一个用 Javascript 编写的函数，我的 html 文件有

<script type="text/javascript" src="javascript.js"></script>

在里面。该页面上的 Javascript 函数无法正常工作，并且控制台显示该函数未定义。我想知道我做错了什么，任何意见将不胜感激。

var player = 0;
var xvalue = 0;
var ovalue = 0;
function tic(a) 
{
    if(player === 0)
    {
        document.getElementById(a).value = 'X';
        document.getElementById(a).disabled = 'true';
        player = 1;
        if(a === 'aa'){
            var i = 1;
            for(i = 1; i <= 1; i++; ){
                xvalue++;
            }
        }
        else if(a === 'ab'){
            var i = 1;
            for(i = 1; i <= 2; i++; ){
                xvalue++;
            }
        }
        else if(a === 'ac'){
            var i = 1;
            for(i = 1; i <= 4; i++; ){
                xvalue++;
            }
        }
        else if(a === 'ba'){
            var i = 1;
            for(i = 1; i <= 8; i++; ){
                xvalue++;
            }
        }
        else if(a === 'bb'){
            var i = 1;
            for(i = 1; i <= 16; i++; ){
                xvalue++;
            }
        }
        else if(a === 'bc'){
            var i = 1;
            for(i = 1; i <= 32; i++; ){
                xvalue++;
            }
        }
        else if(a === 'ca'){
            var i = 1;
            for(i = 1; i <= 64; i++; ){
                xvalue++;
            }
        }
        else if(a === 'cb'){
            var i = 1;
            for(i = 1; i <= 128; i++; ){
                xvalue++;
            }
        }
        else if(a === 'cc'){
            var i = 1;
            for(i = 1; i <= 256; i++; ){
                xvalue++;
            }
        }
        if(xvalue === 448){
            alert("player 1 wins!");
        }
        else if(xvalue === 7){
            alert("player 1 wins!");
        }
        else if(xvalue === 56){
            alert("player 1 wins!");
        }
        else if(xvalue === 273){
            alert("player 1 wins!");
        }
        else if(xvalue === 84){
            alert("player 1 wins!");
        }
        else if(xvalue === 73){
            alert("player 1 wins!");
        }
        else if(xvalue === 146){
            alert("player 1 wins!");
        }
        else if(xvalue === 292){
            alert("player 1 wins!");
        }
    }
    else
    {
        document.getElementById(a).value = 'O';
        document.getElementById(a).disabled = 'true';
        player = 0;
    }
}

Answer 1

我运行你的脚本，得到:SyntaxError: Unexpected token ;

所以，你在循环中出错了:

 for(i = 1; i <= 256; i++; ){

正确的方法是:

 for(i = 1; i <= 256; i++ ){

删除;

因此，正确的代码是:

var player = 0;
var xvalue = 0;
var ovalue = 0;
function tic(a) 
{
    if(player === 0)
    {
        document.getElementById(a).value = 'X';
        document.getElementById(a).disabled = 'true';
        player = 1;
        if(a === 'aa'){
            var i = 1;
            for(i = 1; i <= 1; i++ ){
                xvalue++;
            }
        }
        else if(a === 'ab'){
            var i = 1;
            for(i = 1; i <= 2; i++ ){
                xvalue++;
            }
        }
        else if(a === 'ac'){
            var i = 1;
            for(i = 1; i <= 4; i++ ){
                xvalue++;
            }
        }
        else if(a === 'ba'){
            var i = 1;
            for(i = 1; i <= 8; i++ ){
                xvalue++;
            }
        }
        else if(a === 'bb'){
            var i = 1;
            for(i = 1; i <= 16; i++ ){
                xvalue++;
            }
        }
        else if(a === 'bc'){
            var i = 1;
            for(i = 1; i <= 32; i++ ){
                xvalue++;
            }
        }
        else if(a === 'ca'){
            var i = 1;
            for(i = 1; i <= 64; i++ ){
                xvalue++;
            }
        }
        else if(a === 'cb'){
            var i = 1;
            for(i = 1; i <= 128; i++ ){
                xvalue++;
            }
        }
        else if(a === 'cc'){
            var i = 1;
            for(i = 1; i <= 256; i++ ){
                xvalue++;
            }
        }
        if(xvalue === 448){
            alert("player 1 wins!");
        }
        else if(xvalue === 7){
            alert("player 1 wins!");
        }
        else if(xvalue === 56){
            alert("player 1 wins!");
        }
        else if(xvalue === 273){
            alert("player 1 wins!");
        }
        else if(xvalue === 84){
            alert("player 1 wins!");
        }
        else if(xvalue === 73){
            alert("player 1 wins!");
        }
        else if(xvalue === 146){
            alert("player 1 wins!");
        }
        else if(xvalue === 292){
            alert("player 1 wins!");
        }
    }
    else
    {
        document.getElementById(a).value = 'O';
        document.getElementById(a).disabled = 'true';
        player = 0;
    }
}