for循环嵌套

Question

我有两个数组 A，B，然后我拿到A的面的每一个值去跟B里面的每一个值进行对比，有的话就取出A放在数组里，如果没有就在数组里补个空，这个循环要怎么写，本来A的长度都是12，结果返回了一个A*B长度的数组，但是我想返回的还是长度是12的数组,只不过A里有的，B没有，就在对应的位置补空

Answer 1

A.map(v=>B.indexOf(v)<0?"":v)var A = ["a","b","c"];var B = ["b"];function func(A,B){&nbsp; &nbsp; var arr = [];&nbsp; &nbsp; var str = "";&nbsp; for(var i=0;i<A.length;i++){&nbsp; &nbsp; &nbsp; str = "";&nbsp; &nbsp; &nbsp; for(var j=0;j<B.length;j++){&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if(A[i]==B[j]){&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; str = A[i]//相等把 值 加进数组&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; break;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; arr.push(str)&nbsp; }return arr;}console.log(func(A,B))//["","b",""]