javascript - Why do variables in the global scope get assigned to the window object? - 


var foo = 'bar'; console.log(window.foo); // bar

seems variables assigned properties this, inside anonymous functions, this refers parent scope, doesn't assign variables parent scope.

function() {     var foo = 'bar'; }();  window.foo; // undefined

what object variables assigned in non-global scopes?

to cite http://perfectionkills.com/understanding-delete/#execution_context:

every execution context has so-called variable object associated it. execution context, variable object abstract entity, mechanism describe variable instantiation. now, interesing part variables , functions declared in source text added properties of variable object.

when control enters execution context global code, global object used variable object. precisely why variables or functions declared globally become properties of global object

yet, these variable objects not accessible. non-internal 1 global object, window or this (in global context).

the relevant section in specification #10: executable code , execution contexts.


Comments

Post a Comment

Popular posts from this blog

javascript - Jquery show_hide, what to add in order to make the page scroll to the bottom of the hidden field once button is clicked -

i have button on website when clicked, reveals map. button can seen when page first loads up, when clicked, section holding map slides open , goes out of screen since page loads @ top (normal). want page scroll down bottom of div select when button pushed, if map out of screen. if page scrolled down, , clicks show map button, don't want page jump bottom of map. i tried figure out myself, no luck. seasoned jquery coders able give me guidance? many thanks! map = mapdiv.gmap3("get"); infobox = new infobox({ pixeloffset: new google.maps.size(-220, -310), closeboxurl: '', enableeventpropagation: true }); mapdiv.delegate('.infobox .close','click',function () { infobox.close(); }); jquery(".slidingdiv").hide(); jquery(".show_hide").show(); jquery('.show_hide').click(function(){ lastcenter=map.getcenter(); jquery(".slidingdiv&quo
Read more

javascript - Highcharts multi-color line -

Image
i looking create highchart multi-colored line. if goes down under value, become red, , when comes on value, become green . here picture example: or maybe highcharts have other charts models differentiate high or low level color? you can achieve coloring using lineargradient coloring: color: { lineargradient: { x1: 0, x2: 0, y1: 0, y2: 1 }, stops: [ [0, 'red'], [0.25, 'yellow'], [0.50, 'green'], [0.75, 'yellow'], [1, 'red'] ] } here 0 in stops relates minimum value of series , 1 maximum value, , in between percentages between values. if find percentages according values prior creating chart use correct stops values make relate specific values in data (at least approximately). see this jsfiddle example .
Read more

javascript - Enter key does not work in search box -

tried search guys sorry. input in search box doesnt work (or search) when hit enter when user clicks search button. doing wrong? here code. thanks. <script type="text/javascript"> $(document).ready(function() { $("#submit").click(function() { var url = "http://asla.org/awardssearch.html"; url += "?s=" + $('#googlecse').val(); window.location = url; }); $('#googlecse').keydown(function(event) { if (event.keycode == '13') { $("#submit").click(); } else { //do nothing :) } }); }); </script> <form class="navbar-form navbar-right" role="search"> <div class="search"> <input id="googlecse" type="text" onblur="if(this.value=='')this.value=this.defaultvalue;" onfocus="if(this.value==this.defaultvalue)t
Read more