revision

Prompt

• The prompt() method displays a dialog box that prompts the visitor for input.
• A prompt box is often used if you want the user to input a value before entering a page.
• A prompt is text or symbols used to represent the system's readiness to perform the next command. A prompt may also be a text representation of where the user is currently.

Alert

• An alert dialog box is mostly used to give a warning message to the users. For example, if one input field requires to enter some text but the user does not provide any input, then as a part of validation, you can use an alert box to give a warning message.

Var/Variable

• Variable declarations, wherever they occur, are processed before any code is executed. The scope of a variable declared with var is its current execution context, which is either the enclosing function or, for variables declared outside any function, global.

Concatenate

• OperatorDescription+Addition-Subtraction*Multiplication/Division%Modulus++Increment--Decrement

Increment

• An increase or addition, especially one of a series on a fixed scale. all sizes from 4–30 mm in 1 mm increments.
• Cause a discrete increase in (a numerical quantity).

Decrement

• cause a discrete reduction in (a numerical quantity).the instruction decrements the accumulator by one.

Selection

• Also called a decision, one of the three basic logic structures in computer programming. The other two logic structures are sequence and loop. In a selection structure, a question is asked, and depending on the answer, the program takes one of two courses of action, after which the program moves on to the next event.

Iteration

• Each repetition of the process is also called an "iteration", and the results of one iteration are used as the starting point for the next iteration. In the context of mathematics or computer science, iteration (along with the related technique of recursion) is a standard building block of algorithms.