coveredBy

Returns true if geometry a lies in geometry b.

Geometry a is covered by geometry b if all points of a are in the interior or at the boundary of b.

If either geometry is empty, returns false.

coveredBy is the converse of covers: coveredBy(a, b) === covers(b, a).

warning

Do not use this function with invalid geometries. You will get unexpected results.

Parameters

Name	Type	Description
a	Geometry | Prepared<Geometry>	First geometry
b	Geometry	Second geometry

Returns

boolean

true if geometry a is covered by geometry b

Throws

• GEOSError on unsupported geometry types (curved)

See also

• covers converse of coveredBy
• within less inclusive coveredBy
• prepare improves performance of repeated calls against a single geometry

Examples

differences with 'within'

const a = point([ 2, 0 ]);
const b = lineString([ [ 0, 3 ], [ 4, 5 ], [ 2, 0 ] ]);
const ab_within = within(a, b); // false
const ab_coveredBy = coveredBy(a, b); // true

const g = lineString([ [ 12, 2 ], [ 14, 2 ], [ 14, 4 ] ]);
const h = polygon([
    [ [ 10, 0 ], [ 10, 5 ], [ 15, 5 ], [ 15, 0 ], [ 10, 0 ] ],
    [ [ 12, 2 ], [ 14, 2 ], [ 14, 4 ], [ 12, 4 ], [ 12, 2 ] ],
]);
const gh_within = within(g, h); // false
const gh_coveredBy = coveredBy(g, h); // true

const a = point([ 2, 0 ]); const b = lineString([ [ 0, 3 ], [ 4, 5 ], [ 2, 0 ] ]); const ab_within = within(a, b); // false const ab_coveredBy = coveredBy(a, b); // true const g = lineString([ [ 12, 2 ], [ 14, 2 ], [ 14, 4 ] ]); const h = polygon([ [ [ 10, 0 ], [ 10, 5 ], [ 15, 5 ], [ 15, 0 ], [ 10, 0 ] ], [ [ 12, 2 ], [ 14, 2 ], [ 14, 4 ], [ 12, 4 ], [ 12, 2 ] ], ]); const gh_within = within(g, h); // false const gh_coveredBy = coveredBy(g, h); // true