javascript 什么是标志变量？
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What is a flag variable?
提问by HIRA THAKUR
Recently I came across flag variables, but I have no idea what they do.
最近我遇到了标志变量，但我不知道它们是做什么的。
I am little unsure about when to use a flag variable and how to go about it.
我不太确定何时使用标志变量以及如何使用它。
I Googled it but there weren't any specific examples related to my context (of JavaScript).
我在谷歌上搜索了它，但没有任何与我的上下文（JavaScript）相关的具体示例。
回答by Danny Beckett
Flag Variables Defined and Usessays:
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. Using flag variable(user defined variable, not a predefined) you can control the flow of a function or statement, allowing you to check for certain conditions while your function progresses.
标志变量，最简单的形式，是您定义的一个变量，直到某些条件为真时才具有一个值，在这种情况下，您可以更改变量的值。使用标志变量（用户定义的变量，而不是预定义的），您可以控制函数或语句的流程，允许您在函数进行时检查某些条件。
As an example:
举个例子：
// errors is the flag var
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!");回答by sajin
A flag is a variable used to have some value until some condition becomes true,then we change it to false and print the output (Initially flag considered as true)
标志是一个变量，用于在某些条件变为真之前具有某些值，然后我们将其更改为假并打印输出（最初将标志视为真）
回答by sajin
Flag variables are the same for all languages, whether it's RUBY, Python, Javascript or C++.
所有语言的标志变量都是相同的，无论是 RUBY、Python、Javascript 还是 C++。
A flag variable is usually given one value, 0or 1, Trueor False. It's used as a Boolean variable where the result toggles between 0 (False) and 1 (True) or as used by the programmer. Some prefer flag = 0and change it to flag = 1in the program to perform an action.
标志变量通常被赋予一个值，0或1，True或False。它用作布尔变量，其中结果在 0 (False) 和 1 (True) 之间切换或由程序员使用。有些人更喜欢flag = 0并将其更改为flag = 1在程序中执行操作。
回答by Aryan Beezadhur
No matter what language you are using, the concept of flag variables is always the same: a variable that stores a booleanvalue. A boolean value is one which is always either trueor falseor is either 0or 1(depending on the language and programmer's personal preference).
无论您使用哪种语言，标志变量的概念始终相同：存储布尔值的变量。布尔值是一个始终为true或false或为0或1（取决于语言和程序员的个人偏好）的值。
Flag variables (also called boolean variables, or often just flags) are used to indicate a condition which can only be either of the two boolean values. The value of the variable can toggle depending on events in the program.
标志变量（也称为boolean variables，或通常只是flags）用于指示只能是两个布尔值之一的条件。变量的值可以根据程序中的事件切换。
A JavaScript example:
一个 JavaScript 示例：
var isRaining = false; // It is either raining or not raining.
var statusCode = true; // Status codes may be boolean values.
