Merge pull request #31089 from pawkrol/master

Add import function to MathJS types

types/mathjs/index.d.ts

@@ -3,6 +3,7 @@
 // Definitions by: Ilya Shestakov <https://github.com/siavol>,
 //                  Andy Patterson <https://github.com/andnp>,
 //                  Brad Besserman <https://github.com/bradbesserman>
+//                  Pawel Krol <https://github.com/pawkrol>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.2
 
@@ -2571,6 +2572,23 @@ declare namespace math {
          * ‘string’, ‘Array’, ‘Date’.
          */
         typeof(x: any): string;
+
+        /**
+         * Import functions from an object or a module
+         * To avoid errors when using one of the imported functions extend module like this:
+         *
+         * @example
+         * // imported_math_functions.ts
+         * declare module 'mathjs' {
+         *      interface MathJsStatic {
+         *          hello(a: number): number;
+         *      }
+         * }
+         *
+         * @param object An object with functions to be imported.
+         * @param options An object with import options.
+         */
+        import(object: ImportObject | ImportObject[], options: ImportOptions): void;
     }
 
     interface Matrix {
@@ -4542,4 +4560,14 @@ declare namespace math {
          */
         typeof(): MathJsChain;
     }
+
+    interface ImportOptions {
+        override?: boolean;
+        silent?: boolean;
+        wrap?: boolean;
+    }
+
+    interface ImportObject {
+        [key: string]: any;
+    }
 }

types/mathjs/mathjs-tests.ts

@@ -1,3 +1,6 @@
+// Import needed for mathjs.import functionality (declaring/extending module)
+import * as math from 'mathjs';
+
 /*
 Basic usage examples
 */
@@ -392,3 +395,27 @@ JSON serialization/deserialization
 	const parsed = JSON.parse(stringified, math.json.reviver);
 	parsed.bigNumber === math.bignumber('1.5'); // true
 }
+
+/*
+Extend functionality with import
+ */
+
+declare module 'mathjs' {
+    interface MathJsStatic {
+        testFun(): number;
+        value: number;
+    }
+}
+
+{
+    const testFun = () => 5;
+
+    math.import({
+        testFun,
+        value: 10
+    }, {});
+
+    math.testFun();
+
+    const a = math.value * 2;
+}