我不明白这段代码。
var timesTable;
while ((timesTable = prompt("Enter the times table", -1)) != -1) {.....}
为什么有必要在之前声明变量?我试着这样做:
while ((var timesTable = prompt("Enter the times table", -1)) != -1) {.....}
但它不起作用。有什么问题?是关于范围的吗?
完整的计划是:
function writeTimesTable(timesTable, timesByStart, timesByEnd) {
for (; timesByStart <= timesByEnd; timesByStart++) {
document.write(timesTable + " * " + timesByStart + " = " + timesByStart * timesTable + "<br />");
}
}
var timesTable;
while ((timesTable = prompt("Enter the times table", -1)) != -1) {
while (isNaN(timesTable) == true) {
timesTable = prompt(timesTable + " is not a " + "valid number, please retry", -1);
}
document.write("<br />The " + timesTable + " times table<br />");
writeTimesTable(timesTable, 1, 12);
}
先谢谢。