Javascript nested scope

Question

var landscape = function() {

  var result = "";

  var flat = function(size) {

    for (var count = 0; count < size; count++)
      result += "_";
  };

  var mountain = function(size) {

    result += "/";
    for (var count = 0; count < size; count++)
      result += "'"; //this statement comes first so ,"'" should print first 
    result += "\\"; //Then this should print "\"

/*
loop will run 4 times. it should print /'\'\'\' to my understanding.
*/



  };

  flat(3);

  mountain(4);

  flat(6);

  mountain(1);

  flat(1);

  return result;
};

console.log(landscape());

Why is this returning :_ _ _ / ' ' ' ' \\_ _ _ _ _ _/ ' \\ _

How I think it should return:_ _ _ / ' \ ' \ ' \ ' \ _ _ _ _ _ _ / ' \ _

Please help me understand why its returning like that?

I'm not sure why it isn't returning a single slash, but according to your code, for mountain, it just adds a "'" for each iteration of the loop. Whenever you don't use the curly bracket notation for the for loop, it only uses the next "line" of code. If you want the desired output, you will have to put the result += "\\"; inside of curly brackets with the result += "'"; — TheCrzyMan
– TheCrzyMan, Commented May 17, 2014 at 3:42

Jonathan Lonowski · Accepted Answer · 2014-05-17 03:59:55Z

4

The \ only appear once per mountain() because it's not being repeated within the for loop.

Loops only use the 1st statement that follows them, similar to doing:

for (var count = 0; count < size; count++) {
  result += "'";  // appended for each `count`
}
result += "\\";   // appended once after the loop has completed

To achieve the output you're expecting, a block would have to be added around both statements so they repeat together:

for (var count = 0; count < size; count++) {
  result += "'";
  result += "\\";
}

edited May 17, 2014 at 3:59

answered May 17, 2014 at 3:44

Jonathan Lonowski

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4 Comments

user3525853 Over a year ago

@jonathna the code i have on here is exactly from the book and when i run it it gives me this result : ___/''''______/'_ But in the code, this comes wihtout the curly on the for loop. Thats why im confused.

Jonathan Lonowski Over a year ago

@user3525853 From which book?

user3525853 Over a year ago

the book is called eloquent javascript eloquentjavascript.net/2nd_edition/preview/03_functions.html scroll down to nested scope

Mike Over a year ago

@user3525853 I think you may be confused about how the for loop is functioning. The way it is currently written, it's basically saying "repeat the immediate next statement X amount of times". The immediate next statement is result += "'". After the for loop has done that, program execution continues to the next statement, which is result += "\\"

Mike · Accepted Answer · 2014-05-17 03:42:13Z

3

It won't return '\'\'\ because the \ is only printed after the for loop completes. If curly brackets aren't used with a for loop, it will use only the following instruction. In this case, it will only use the result += "'" instruction and not the result += "\\" instruction.

So, in words, your mountain(4) function is saying:

Add a /
Add 4 '
Add a \

answered May 17, 2014 at 3:42

Mike

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4 Comments

user3525853 Over a year ago

"\" its printed in the loop.

Mike Over a year ago

No it isn't. If there were curly brackets around both statements, it would be. But as it is written, only the apostrophe is in the loop.

user3525853 Over a year ago

so what about the second statement result += "\\". why is that not bieng run?

Mike Over a year ago

It's being run once, after the for loop finishes.

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