iankit3/array_prototype_splice.html

## array_prototype_splice.html
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>JS Bin</title>
</head>
<body>

<script id="jsbin-javascript">
Array.prototype.mySplice = function (start, count, ...elems) {
  let first = this.slice(0, start),
    middle = elems,
    last = this.slice(start + count);
  let arr = [...first, ...middle, ...last];
  this.length = arr.length;

  for (let i = 0; i < this.length; ++i) {
    this[i] = arr[i];
  }
};

(function main() {
  var x, y;

  function reset() {
    x = [1, 2, 3, 4, 5];
    y = [...x];
  }

  let tests = [
    [1, 2],
    [1, 4],
    [1, 4, 12],
    [1, 0, 10, 12],
    [1, 2, 10, 12],
    [1, 4, 10, 12],
    [1, 15, 10, 12],
  ];

  function logAndAssert(x, y) {
    console.log(x, y);
    console.assert(JSON.stringify(x) === JSON.stringify(y));
  }

  tests.forEach((test) => {
    reset();
    console.log(`\n Running - Array.splice(${[...test]})`);
    logAndAssert(x, y);
    x.splice(...test);
    y.mySplice(...test);
    console.log("processed");
    logAndAssert(x, y);
  });
})();
</script>


<script id="jsbin-source-javascript" type="text/javascript">Array.prototype.mySplice = function (start, count, ...elems) {
 Array.prototype.mySplice = function (start, count, ...elems) {
  let first = this.slice(0, start),
    middle = elems,
    last = this.slice(start + count);
  let arr = [...first, ...middle, ...last];
  this.length = arr.length;

  for (let i = 0; i < this.length; ++i) {
    this[i] = arr[i];
  }
};

(function main() {
  var x, y;

  function reset() {
    x = [1, 2, 3, 4, 5];
    y = [...x];
  }

  let tests = [
    [1, 2],
    [1, 4],
    [1, 4, 12],
    [1, 0, 10, 12],
    [1, 2, 10, 12],
  ];

  function logAndAssert(x, y) {
    console.log(x, y);
    console.assert(JSON.stringify(x) === JSON.stringify(y));
  }

  tests.forEach((test) => {
    reset();
    console.log(`\n Running - Array.splice(${[...test]})`);
    logAndAssert(x, y);
    x.splice(...test);
    y.mySplice(...test);
    console.log("processed");
    logAndAssert(x, y);
  });
})();
</script></body>
</html>

## array_prototype_splice.js
Array.prototype.mySplice = function (start, count, ...elems) {
  var end = start + count;
  /*Remove elems b/w start and end
   *   Three steps
   *    1. Mark them as null
   *    2. Move them at the end
   *    3. change the length of the array (removes the nulls if any)
   */

  // 1.
  for (let i = start; i < end; ++i) {
    this[i] = null;
  }

  // 2.
  let len = this.length;
  for (let i = 0; i < len; ++i) {
    if (this[i] == null) {
      this[i] = this[end];
      end++;
    }
  }

  // 3.
  if (this[this.length - 1] == null) {
    this.length -= count;
  }

  /*Add each elem from elems*/
  if (elems.length > 0) {
    let first = this.slice(0, start),
      middle = elems,
      last = this.slice(start + count);
    let arr = [...first, ...middle, ...last];
    this.length = arr.length;

    for (let i = 0; i < this.length; ++i) {
      this[i] = arr[i];
    }
  }
};

(function main() {
  var x, y;

  function reset() {
    x = [1, 2, 3, 4, 5];
    y = [...x];
  }

  let tests = [
    [1, 2],
    [1, 4],
    [1, 4, 12],
    [1, 0, 10, 12],
    [1, 2, 10, 12],
    [1, 4, 10, 12],
    [1, 15, 10, 12],
  ];

  function logAndAssert(x, y) {
    console.log(x, y);
    console.assert(JSON.stringify(x) === JSON.stringify(y));
  }

  tests.forEach((test) => {
    reset();
    console.log(`\n Running - Array.splice(${[...test]})`);
    logAndAssert(x, y);
    x.splice(...test);
    y.mySplice(...test);
    console.log("processed");
    logAndAssert(x, y);
  });
})();
	<!DOCTYPE html>
	<html>
	<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width">
	<title>JS Bin</title>
	</head>
	<body>

	<script id="jsbin-javascript">
	Array.prototype.mySplice = function (start, count, ...elems) {
	let first = this.slice(0, start),
	middle = elems,
	last = this.slice(start + count);
	let arr = [...first, ...middle, ...last];
	this.length = arr.length;

	for (let i = 0; i < this.length; ++i) {
	this[i] = arr[i];
	}
	};

	(function main() {
	var x, y;

	function reset() {
	x = [1, 2, 3, 4, 5];
	y = [...x];
	}

	let tests = [
	[1, 2],
	[1, 4],
	[1, 4, 12],
	[1, 0, 10, 12],
	[1, 2, 10, 12],
	[1, 4, 10, 12],
	[1, 15, 10, 12],
	];

	function logAndAssert(x, y) {
	console.log(x, y);
	console.assert(JSON.stringify(x) === JSON.stringify(y));
	}

	tests.forEach((test) => {
	reset();
	console.log(`\n Running - Array.splice(${[...test]})`);
	logAndAssert(x, y);
	x.splice(...test);
	y.mySplice(...test);
	console.log("processed");
	logAndAssert(x, y);
	});
	})();
	</script>



	<script id="jsbin-source-javascript" type="text/javascript">Array.prototype.mySplice = function (start, count, ...elems) {
	Array.prototype.mySplice = function (start, count, ...elems) {
	let first = this.slice(0, start),
	middle = elems,
	last = this.slice(start + count);
	let arr = [...first, ...middle, ...last];
	this.length = arr.length;

	for (let i = 0; i < this.length; ++i) {
	this[i] = arr[i];
	}
	};

	(function main() {
	var x, y;

	function reset() {
	x = [1, 2, 3, 4, 5];
	y = [...x];
	}

	let tests = [
	[1, 2],
	[1, 4],
	[1, 4, 12],
	[1, 0, 10, 12],
	[1, 2, 10, 12],
	];

	function logAndAssert(x, y) {
	console.log(x, y);
	console.assert(JSON.stringify(x) === JSON.stringify(y));
	}

	tests.forEach((test) => {
	reset();
	console.log(`\n Running - Array.splice(${[...test]})`);
	logAndAssert(x, y);
	x.splice(...test);
	y.mySplice(...test);
	console.log("processed");
	logAndAssert(x, y);
	});
	})();
	</script></body>
	</html>
	Array.prototype.mySplice = function (start, count, ...elems) {
	var end = start + count;
	/*Remove elems b/w start and end
	* Three steps
	* 1. Mark them as null
	* 2. Move them at the end
	* 3. change the length of the array (removes the nulls if any)
	*/

	// 1.
	for (let i = start; i < end; ++i) {
	this[i] = null;
	}

	// 2.
	let len = this.length;
	for (let i = 0; i < len; ++i) {
	if (this[i] == null) {
	this[i] = this[end];
	end++;
	}
	}

	// 3.
	if (this[this.length - 1] == null) {
	this.length -= count;
	}

	/Add each elem from elems/
	if (elems.length > 0) {
	let first = this.slice(0, start),
	middle = elems,
	last = this.slice(start + count);
	let arr = [...first, ...middle, ...last];
	this.length = arr.length;

	for (let i = 0; i < this.length; ++i) {
	this[i] = arr[i];
	}
	}
	};

	(function main() {
	var x, y;

	function reset() {
	x = [1, 2, 3, 4, 5];
	y = [...x];
	}

	let tests = [
	[1, 2],
	[1, 4],
	[1, 4, 12],
	[1, 0, 10, 12],
	[1, 2, 10, 12],
	[1, 4, 10, 12],
	[1, 15, 10, 12],
	];

	function logAndAssert(x, y) {
	console.log(x, y);
	console.assert(JSON.stringify(x) === JSON.stringify(y));
	}

	tests.forEach((test) => {
	reset();
	console.log(`\n Running - Array.splice(${[...test]})`);
	logAndAssert(x, y);
	x.splice(...test);
	y.mySplice(...test);
	console.log("processed");
	logAndAssert(x, y);
	});
	})();