确定数组A中是否所有元素都存在于数组B中

Question

So this is the code:

var array_A = [1,2,4];
var array_B = [1,2,3,4];

I need a function that for the case above will print TRUE. Because

1,2 and 4 

are present in array_B.

The function will print FALSE if the declaration is as following:

var array_A = [1,2,4,5];
var array_B = [1,2,3,4];

Because

"5" 

is not present in array_B.

I guess this is quite easy to accomplish with lodash or underscore. But could not find exactly what I was looking for. Any hint?

Answer 1

Use array every and indexOf:

 var array_A = [1,2,4]; var array_B = [1,2,3,4]; var result = array_A.every(el => array_B.indexOf(el) !== -1); console.log(result); 

Answer 2

You could use Array#includes with Array#forEach .

 var array_A = [1, 2, 4], array_B = [1, 2, 3, 4], result = array_A.every(a => array_B.includes(a)); console.log(result);