Another one!
let result_x000D_
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const givenStr = 'A, X' //values separated by comma or space._x000D_
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const allowed = ['A', 'B']_x000D_
const given = givenStr.split(/[\s,]+/).filter(v => v)_x000D_
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console.log('given (array):', given)_x000D_
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// given contains none or only allowed values:_x000D_
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result = given.reduce((acc, val) => {_x000D_
return acc && allowed.includes(val)_x000D_
}, true)_x000D_
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console.log('given contains none or only allowed values:', result)_x000D_
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// given contains at least one allowed value:_x000D_
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result = given.reduce((acc, val) => {_x000D_
return acc || allowed.includes(val)_x000D_
}, false)_x000D_
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console.log('given contains at least one allowed value:', result)
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