Hi Alexandre, Don't go adopting a coding practice just because of a single mailing list message. :-)
There's nothing wrong with quoting property names in an object literal, but the majority of experienced JavaScript programmers do not quote them except when necessary. As an example, browse through the jQuery source code: http://ajax.googleapis.com/ajax/libs/jquery/1.2.6/jquery.js Most of the property names in the code are not quoted, except for those few that are invalid identifiers or reserved words. Regarding setTimeout and setInterval, a minor nitpick on terminology: "setTimeout and setInterval scope the called function to the window object". Actually, the *scope* of the called function is determined by its position in the source code. JavaScript uses lexical scoping, where a nested function can directly refer to variables declared in outer functions or in the global scope. That's why your setInterval callback is able to use your thisObj variable, because the interpreter follows the scope chain from the inner function up to the outer function and finds the variable there. What you're talking about is the value of "this" in the setInterval callback. setInterval and setTimeout call your callback function as a method of the global object (which is the window object in a browser). Or another way to put it is that they don't call the function as a method of any object at all, and by default "this" is set to the global object. In any case, terminology nitpicks aside, your code is the right way to solve the problem! :-) -Mike > From: Alexandre Plennevaux > > hi donb, according to a lengthy discussion we had on this > mailinglist yesterday the quotes are good practice. see: > http://groups.google.com/group/jquery-en/msg/821f4eb134c51d3d > (is is just one message on a 31-long thread, if u have time > ,read the whole thread it is interesting ) > > As for this issue after extensive googling i found out that > setTimeout and setInterval scope the called function to the > window object, not the object the setinterval is called in. > > Therefore here is how to do it: > > var datascape = { > 'mouseX': 0, > 'myInterval': 0, > 'create': function(){ > > var thisObj = this; //<-- store this object instance in a variable > > $('#datascape').bind('mousemove', function(e) > { > this.mouseX = e.pageX; > }).bind("mouseover", function() > { > datascape.myInterval = setInterval(function() { > thisObj.move(); }, 1000); // <-- use the vairable > referencing the instance > > }).bind("mouseout", function() > { > clearInterval(datascape.myInterval); > }); > }, > > 'move': function(){ > $.log('datascape.move : mouseX = ' + this.mouseX); > } > } > > On Thu, Jan 1, 2009 at 3:46 PM, donb > <falconwatc...@comcast.net> wrote: > > > > You should change 'move' to move (remove apostrophes). > > > > > > On Jan 1, 9:01 am, "Alexandre Plennevaux" <aplennev...@gmail.com> > > wrote: > >> Hello mates, > >> > >> i have an object datascape which among other things, contains a > >> property storing the mouse position, and a function that uses that > >> property. Inside another method i > >> > >> var datascape = { > >> 'mouseX': 0, > >> 'myInterval': 0, > >> 'create': function(){ > >> $('#datascape').bind('mousemove', function(e) > >> { > >> this.mouseX = e.pageX; > >> }).bind("mouseover", function() > >> { > >> this.myInterval = setInterval(this.move, 200); > >> > >> }).bind("mouseout", function() > >> { > >> clearInterval(this.myInterval); > >> }); > >> }, > >> > >> 'move': function(){ > >> $.log('datascape.move : mouseX = ' + this.mouseX); > >> } > >> > >> } > >> > >> Yet the script does not work: > >> firebug console points at the setInterval call, saying: > >> > >> useless setInterval call (missing quotes around > >> argument?)http://localhost/prototype/_js/frontend/proto.03.js > >> Line 172 > >> > >> can someone help me / explain what i'm doing wrong ? > >> > >> Thank you, > >> > >> Alexandre > >> > >> PS: to all jquerians: happy 2009 !! >
