(feature) added from and of static methods

Author: vigan-abd

src/array.js

@@ -582,6 +582,57 @@ class ArrayT extends GenericType {
     return value instanceof ArrayT
   }
 
+  /**
+   * @param {string|Function} type
+   * @param  {...any} values
+   * @returns {ArrayT}
+   */
+  static of (type, ...values) {
+    return new ArrayT(type, ...values)
+  }
+
+  /**
+   * @param {string|Function} type
+   * @param {(value: any, index?: number, array?: ArrayT) => any} cb
+   * @param {*} thisArg
+   * @returns {ArrayT}
+   */
+  static from (type, values, cb = null, thisArg = null) {
+    const res = new ArrayT(type)
+    if (values[Symbol.iterator]) {
+      const it = values[Symbol.iterator]()
+      let next = it.next()
+      let i = 0
+      while (!next.done) {
+        if (cb) {
+          const mappedItem = thisArg ? cb.call(thisArg, next.value, i, res) : cb(next.value, i, res)
+          res.push(mappedItem)
+        } else {
+          res.push(next.value)
+        }
+        next = it.next()
+        i++
+      }
+    } else if (typeof values === 'object' && values.length) { // { length: x }
+      const length = Number(values.length)
+      if (Number.isNaN(length)) return res
+      if (!Number.isFinite(length)) throw new RangeError('Invalid array length')
+
+      for (let i = 0; i < length; i++) {
+        if (cb) {
+          const mappedItem = thisArg ? cb.call(thisArg, undefined, i, res) : cb(undefined, i, res)
+          res.push(mappedItem)
+        } else {
+          res.push(undefined)
+        }
+      }
+    }
+
+    console.log(res)
+
+    return res
+  }
+
   // #### Extended methods ####//
   /**
    * @returns {ArrayT}

test/array.test.js

@@ -380,6 +380,64 @@ module.exports = () => {
       expect(arr.toArray()).to.be.eql([0, 1, 2, 3, 4, 5, 6, 7])
     })
 
+    it('from - it should support iterables', () => {
+      expect(ArrayT.from('number', 1, 2, 3)).to.be.instanceOf(ArrayT)
+      expect(ArrayT.from('string', 'foo').toArray()).to.be.eql(['f', 'o', 'o'])
+      expect(ArrayT.from('number', [1, 2, 3], x => x + x).toArray()).to.be.eql([2, 4, 6])
+      expect(
+        ArrayT.from('string', new Set(['foo', 'bar', 'baz', 'foo'])).toArray()
+      ).to.be.eql(['foo', 'bar', 'baz'])
+      expect(
+        ArrayT.from(Array, new Map([[1, 2], [2, 4], [4, 8]])).toArray()
+      ).to.be.eql([[1, 2], [2, 4], [4, 8]])
+      expect(
+        ArrayT.from('string', new Map([['1', 'a'], ['2', 'b']]).values()).toArray()
+      ).to.be.eql(['a', 'b'])
+      expect(
+        ArrayT.from('string', new Map([['1', 'a'], ['2', 'b']]).keys()).toArray()
+      ).to.be.eql(['1', '2'])
+    })
+
+    it('from - it should support objects with length property', () => {
+      expect(
+        ArrayT.from('number', { length: 5 }, (_, i) => i).toArray()
+      ).to.be.eql([0, 1, 2, 3, 4])
+    })
+
+    it('from - it should return empty array on unsupported object type', () => {
+      expect(ArrayT.from('string', { foo: 'bar' }).toArray()).to.be.eql([])
+    })
+
+    it('from - it should return empty array in case of negative length', () => {
+      expect(
+        ArrayT.from('number', { length: -3 }).toArray()
+      ).to.be.eql([])
+    })
+
+    it('from - it should return empty array in case of NaN length', () => {
+      expect(
+        ArrayT.from('number', { length: 'a3' }).toArray()
+      ).to.be.eql([])
+    })
+
+    it('from - it should throw an error in case of infinite length', () => {
+      expect(() => {
+        ArrayT.from('number', { length: Infinity }, (_, i) => i)
+      }).to.throw()
+    })
+
+    it('from - it should throw an error in case of invalid type', () => {
+      expect(() => {
+        ArrayT.from(typeof undefined, { length: 2 }).toArray()
+      }).to.be.throw()
+      expect(() => {
+        ArrayT.from('number', { length: 3 }, (v) => v)
+      }).to.throw()
+      expect(() => {
+        ArrayT.from('number', [1, 2, 3, '4'])
+      }).to.throw()
+    })
+
     it('includes - it should return true if array includes element', () => {
       expect(new ArrayT('number', 1, 2, 3).includes(2)).to.be.true()
       expect(new ArrayT('string', 'a', 'b', 'c').includes('b')).to.be.true()
@@ -453,7 +511,7 @@ module.exports = () => {
     })
 
     it('isArrayT - it should return true if value is instance of ArrayT', () => {
-      class ArrayB extends ArrayT {}
+      class ArrayB extends ArrayT { }
       expect(ArrayT.isArrayT(new ArrayT('number', 1, 2))).to.be.true()
       expect(ArrayT.isArrayT(new ArrayB('number'))).to.be.true()
     })
@@ -604,6 +662,13 @@ module.exports = () => {
       expect(arr.toArray()).to.be.eql([0, 1, 2, 3, 4, 5, 6, 7])
     })
 
+    it('of - it should generate an array from the values', () => {
+      expect(ArrayT.of('number', 1, 2, 3)).to.be.instanceOf(ArrayT)
+      expect(ArrayT.of('number', 1, 2, 3).toArray()).to.be.eql([1, 2, 3])
+      expect(ArrayT.of('number', 5).toArray()).to.be.eql([5])
+      expect(ArrayT.of('number').toArray()).to.be.eql([])
+    })
+
     it('pop - it should behave like array', () => {
       const numArray = new ArrayT('number', 2, 3)
       expect(numArray.pop()).to.be.equal(3)