javascriptvariablesflags

What is a flag variable?


Recently I came across flag variables, but I have no idea what they do.

I am little unsure about when to use a flag variable and how to go about it.

I Googled it but there weren't any specific examples related to my context (of JavaScript).


Solution

  • Flag Variables Defined and Uses says:

    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.

    As an example:

    // 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!");
    }