js for循環,會遇到undefined

node2:/var/www/html/js# node2:/var/www/html/js#cat h23.js var narr=['a','b','c','d','e']; console.log(narr); for (var j=0;j<narr.length;j++){ console.log(j+'=>'+narr[j]); }; console.log(narr); for

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