问对象中的对象和分配原型

EN

function extend(obj, props) {
  for (var prop in props) {
    if (props.hasOwnProperty(prop)) {
      obj[prop] = props[prop];
    }
  }
}

function Block(left, right, up, down) {
  this.left = left || -10; // for default values
  this.right = right || 515;
  this.up = up || 0;
  this.down = down || 600;
}

function BlockProto(obj) {
  extend(this, obj);
}

BlockProto.prototype.left = -10;
BlockProto.prototype.right = 515;
BlockProto.prototype.up = 0;
BlockProto.prototype.down = 600;

function Level2blocks() {
  this.blocks = {};
}

Level2blocks.prototype.addBlock = function(left, right, up, down) {
  var numOfBlocks = Object.keys(this.blocks).length;
  this.blocks['block' + numOfBlocks] = new Block(left, right, up, down);
};

Level2blocks.prototype.addPrototypeBlock = function(obj) {
  var numOfBlocks = Object.keys(this.blocks).length;
  this.blocks['block' + numOfBlocks] = new BlockProto(obj);
};

var level2Blocks = new Level2blocks();

level2Blocks.addBlock(2, 4, 2, 4);
level2Blocks.addBlock(123, 2, 090, 24);
level2Blocks.addBlock();
level2Blocks.addBlock(undefined, undefined, undefined, 900);

level2Blocks.addPrototypeBlock({});
level2Blocks.addPrototypeBlock({
  left: 4444
});


console.log(level2Blocks.blocks);
console.log(level2Blocks.blocks.block4.left);
console.log(level2Blocks.blocks.block4.right);

var HTMLStr = '<pre>' + JSON.stringify(level2Blocks.blocks, 0, 4) + '</pre>';

HTMLStr += 'Block4 values from prototype: ';
HTMLStr += [level2Blocks.blocks.block4.right, level2Blocks.blocks.block4.left, level2Blocks.blocks.block4.up, level2Blocks.blocks.block4.down].join(', ');

HTMLStr += '<br/> Block5 values from prototype: ';
HTMLStr += [level2Blocks.blocks.block5.right, level2Blocks.blocks.block5.left, level2Blocks.blocks.block5.up, level2Blocks.blocks.block5.down].join(', ');

document.write(HTMLStr);

<div id="out"></div>

var level2blocks = {
    block1: new Block(478, 515, 0, 510),
    block2: new Block(-10, 515, 373, 600)
};