trying to understand some codes related to window.onload in js
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Published on 2013-07-01T03:23:37Z
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2013/07/01
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JavaScript
<body>
<script language="javascript">
window.tdiff = []; fred = function(a,b){return a-b;};
window.onload = function(e){
console.log("window.onload", e, Date.now() ,window.tdiff,
(window.tdiff[1] = Date.now()) && window.tdiff.reduce(fred) );
}
</script>
</body>
Above code is taken from a site.
In firefox->console, it shows:
window.onload load 1372646227664 [undefined, 1372646227664] 1372646227664
Question:
For
window.tdiff->[undefined, 1372646227664], why not:[], because when runs to code:window.tdiff, it is still an empty array?For
window.tdiff.reduce(fred)->1372646227664,window.tdiff = [undefined, 1372646227664],undefined - 1372646227664, should beNaN, why it shows1372646227664?
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