JavaScript. What does this expression mean: " var a = b === c && d; " - 


    // define walk_the_dom function visits every     // node of tree in html source order, starting     // given node. invokes function,     // passing each node in turn. walk_the_dom calls     // process each of child nodes.     var walk_the_dom = function walk(node, func) {         func(node);         node = node.firstchild;         while (node) {             walk(node, func);             node = node.nextsibling;         }     };      // define getelementsbyattribute function.     // takes attribute name string , optional     // matching value. calls walk_the_dom, passing     // function looks attribute name in     // node. matching nodes accumulated in     // results array.     var getelementsbyattribute = function (att, value) {         var results = [];         walk_the_dom(document.body, function (node) {             var actual = node.nodetype === 1 && node.getattribute(att);             if (typeof actual === 'string' &&                     (actual === value || typeof value !== 'string')) {                     results.push(node);                 } });         return results;     };

i don't understand line of code mean:

var actual = node.nodetype === 1 && node.getattribute(att);

how explain kind of expression? 

a = b === xxx && yyy

thanks.

this combination of short-circuiting , fact javascript returns final value of statement. it's same as:

if (b === xxx) {   = yyy; } else {   = false; }

read more here: http://en.wikipedia.org/wiki/short-circuit_evaluation , https://developer.mozilla.org/en/javascript/reference/operators/logical_operators#short-circuit_evaluation


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