Why do results vary based on curly brace placement?

by

That’s one of the pitfalls of JavaScript: automatic semicolon insertion. Lines that do not end with a semicolon, but could be the end of a statement, are automatically terminated, so your first example looks effectively like this: 

function test()
{
  return; // <- notice the inserted semicolon
  { 
    javascript: "fantastic"
  };
}

See also Douglas Crockford’s JS style guide, which mentions semicolon insertion.

In your second example you return an object (built by the curly braces) with the property javascript and its value of "fantastic", effectively the same as this:

function test() {
    var myObject = new Object();
    myObject.javascript = "fantastic";
    return myObject;
}

More Related Contents:

  1. JavaScript Syntax error
  2. What’s the meaning of “=>” (an arrow formed from equals & greater than) in JavaScript?
  3. Add a property to a JavaScript object using a variable as the name?
  4. Location of parenthesis for auto-executing anonymous JavaScript functions?
  5. What do parentheses surrounding an object/function/class declaration mean? [duplicate]
  6. How does this JavaScript/jQuery syntax work: (function( window, undefined ) { })(window)?
  7. What does the leading semicolon in JavaScript libraries do?
  8. Why avoid increment (“++”) and decrement (“–“) operators in JavaScript?
  9. How do I convert a float number to a whole number in JavaScript?
  10. Javascript: Get deep value from object by passing path to it as string [duplicate]
  11. Difference between (function(){})(); and function(){}(); [duplicate]
  12. Immediate function invocation syntax
  13. “var” or no “var” in JavaScript’s “for-in” loop?
  14. Is && statement() the same as if() statement()?
  15. How can I concatenate regex literals in JavaScript?
  16. Javascript Property with three dots (…)
  17. No semicolon before [] is causing error in JavaScript
  18. When should I use a semicolon after curly braces?
  19. Use of commas versus semicolons?
  20. JavaScript error (Uncaught SyntaxError: Unexpected end of input)
  21. How do I remove javascript validation from my eclipse project?
  22. How to convert Set to Array?
  23. Function and variable with the same name
  24. Nested JSON objects – do I have to use arrays for everything?
  25. How can % signs be used in identifiers
  26. When is the ‘javascript:’ prefix valid syntax?
  27. Javascript while loop return value
  28. Using a block’s return value in JavaScript
  29. Javascript history.PushState not working?
  30. + operator before expression in javascript: what does it do?

Leave a Comment