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 power can generate electricity without greenhouse gas emissions. However, there are concerns about its safety. Learn about the safety and health concerns associated with the threat of nuclear meltdowns, as well as the challenges involved in storing radioactive waste.he isotope U-235 is important because it can be used in the nuclear fission chain reaction to create a lot of energy. Unlike the uranium used in a nuclear bomb, which is about 90% enriched with the isotope U-235, the uranium used in a nuclear reactor is only slightly enriched, to about four or five percent.