The only way to truly test if a variable is undefined is to do the following. Remember, undefined is an object in Javascript. To determine if a variable or object property exists, It is good to compare to keyword undefined or you can also check the type of the object to string âundefinedâ. In the following JavaScript code we compare the num to the undefined in both way.
Nuclear waste -- The waste from nuclear power plants will be toxic for humans for more than 100,000 years. Itâs untenable now to secure and store all of the waste from the plants that exist. To scale up to 2,500 or 3,000, let alone 17,000 plants is unthinkable.
Nuclear plants, on the other hand, have three significant nuclear energy cons or problems. The first of these nuclear energy disadvantages is although they are relatively cheap to run, they are extremely expensive to build.At construction costs of up to $4400 per kilowatt-hour, they are extremely expensive to buildâalmost 9 billion dollars for a 2000 megawatt hour plant. Lots of technological advances still to be made will increase efficiency, safety. 2  Small amount of fuel can produce a huge amount of energy. 3  Nuclear fission could solve a lot of the disadvantages. 4  Low emissions source of reliable and constant power generation.