问题描述
Given an array and a value, remove all instances of that value in-place
and return the new length.Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.
Example

Given nums = [3,2,2,3], val = 3,
Your function should return length = 2, with the first two elements of nums being 2.

注意：每次删除一个元素时，注意数组下标的变化

/**
 * @param {number[]} nums
 * @param {number} val
 * @return {number}
 */
var removeElement = function(nums, val) { 
    for(var i = 0; i < nums.length; i++){ 
        if(nums[i] == val){
           nums.splice(i,1);
            i-=1;
        }
    }
    return nums.length;
};