@gmod/jbrowse/src/JBrowse/has.js

JBrowse - client-side genome browser

/**
 * Extends dojo/has with a few additional tests, and makes sure dojo/sniff is loaded.
 */

define([ 'dojo/has', 'dojo/sniff' ],
       function( has ) {

           // does the browser support typed arrays?
           has.add( 'typed-arrays', function() {
                        try {
                            var a = new Uint8Array(1);
                            return !!a;
                        } catch(e) {};
                        return false;
                    });

           // does it support canvas?
           has.add( 'canvas', function() {
                        try {
                            return !! document.createElement('canvas').getContext('2d');
                        } catch(e) {}
                        return false;
                    });

           // some browsers don't do a very good job with
           // percentage-based and fractional-pixel HTML coordinates
           // and sizes
           has.add( 'inaccurate-html-layout', function() {
               return has('safari') || has('ie') < 9;
           }, true );


           has.add( 'save-generated-files', function() {
                        var canSave = false;
                        try {
                            canSave = Blob && !( has('ie') < 10 ) && !( has('safari') < 10 )
                        } catch(e) {}
                        return canSave;
           },true);


           // similar to the inaccurate-html-layout problem, but specifically related to width being 100%
           // rounding on canvas features at the time being
           has.add( 'inaccurate-html-width', function() {
               return has('safari')||has('chrome');
           }, true);

           return has;
       }
);