3 ms·

var NULL = null, TRUE = true, FALSE = false I'm not sure I understand this. Why assign these to variables?

• wendelinsky 14y ago
  That is part of the es6-collections polyfill included as part of smap.js. If I understand correctly, it is for safety (for example you cannot override the value of "true").
  • Twisol 14y ago
    null, true, and false are all keywords. Isn't undefined the only one that can be redefined? (And then it's just equal to void 0.)
    • emwendelin 14y ago
      Yep, you're right. I forgot about that.
• esrauch 14y ago
  I think the reason for these is for js minification. With these assignments a simple minifier will replace those three variables with a line like this: var a=null,b=true,c=false; Then your minified js will be smaller because all other instances of true, false and null will be one character. Whether or not this is a reasonable optimization is debatable but in terms of pure code size it would be a win.
  • ajanuary 14y ago
    Couldn't you build it into the minifier rather than polluting the original source?
    • jackmoore 14y ago
      Yes, stuff like this shouldn't be in the source. UglifyJS and Closure compiler make this optimization, but I've used other js minifiers that did not.