Foreach & add remove elements

参考

http://stackoverflow.com/questions/11058384/how-to-delete-specific-array-elements-from-within-a-foreach-loop-in-javascript

https://gist.github.com/chad3814/2924672

for(var f in fruit) {
    if ( fruit[f] == "pear" ) {
        fruit.splice(f, 1);
    }
}
for(var f in fruit) {
    document.write(fruit[f]+"<br>");
}
//
apple
pear
banana

you should handle it in this way

var fruit = ["apple", "pear", "pear", "pear", "banana"],
    i;
for (i = 0; i < fruit.length; ++i) {
    if (fruit[i] === "pear") {
        fruit.splice(i--, 1);
    }
}
console.log(fruit);
//["apple", "banana"]

原理很显然

当我删除第一个pear的时候 数组是apple pear pear banna

此时继续遍历 将从[2]下标开始 有一个pear就会被忽略