javascript - 什么是标志变量？

Question

最近我遇到了标志变量，但我不知道它们的作用。

我不太确定何时使用标志变量以及如何使用它。

我用 Google 搜索了它，但没有任何与我的(JavaScript)上下文相关的具体示例。

Answer 1

Flag Variables Defined and Uses说:

A flag variable, in its simplest form, is a variable you define to have one value until some condition is true, in which case you change the variable's value. It is a variable you can use to control the flow of a function or statement, allowing you to check for certain conditions while your function progresses.

举个例子:

// errors is the flag variable
var errors = 0;

for(var i = 0; i < 10; i++) {
  if(i == 6) {  // Your error condition
    errors++;
  }
}

if(errors) {  // Is the flag "up"? (i.e. > 0)
  alert("There was a problem!");
}