" in a var statement mean?

2018-06-26 05:24:05

Possible Duplicate:
null coalescing operator for javascript?
What does “options = options || {}” mean in Javascript?

Can someone explain me this expression? I stumbled accros the javascript line of code and I wondered what it means.

var node = element.node || element[element.length - 1].node;

node get's used like this below:

if (node.nextSibling) {
            node.parentNode.insertBefore(this.node, node.nextSibling);
        } else {
            node.parentNode[appendChild](this.node);
        }

At first i though node should be a boolean or something but it's not. Am I correct if i think that the meaning is: node is element.node but if the node attribute is undefined node is the last element in the array of element?

Your understanding is along the right lines; be aware that even if element.node is defined, but is a falsey value ( 0 , false etc.) that element[element.length - 1].node will be assigned to node instead.

Simple answer: it means OR :)

Reference: http://www.w3schools.com/js/js_operators.asp

这意味着，如果element.node的值在布尔表达式中表示为True，那么node将是element.node ，否则它将是element[element.length - 1].node

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