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In this lecture, we are going to explore the concept of a marble diagram sprinkled throughout the documentation

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are these mysterious diagrams.

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They're incredibly helpful for describing behavior of an operator.

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In the resource section of this lecture, I provide a link to the map operator.

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Scrolling through the page, you will find a diagram that looks like this on almost any page.

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You will find a marble diagram to help you understand how the operator works.

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SJS is very verbose.

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They don't shy away from their terminology.

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As wonderful as the documentation is.

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It can be difficult to understand how an observable works just in case.

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Marble diagrams give a clear and concise example of how an operator functions.

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Let's learn how to read a marble diagram, a marble diagram is a visual representation of how an operator

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behaves.

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Operators have inputs and outputs.

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The input refers to the data received by the operator on the output.

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It'll show us the values pushed by the operator.

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Marble diagrams will show us the relationship between the input and output by drawing a horizontal line.

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The line represents the passage of time from left to right.

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Image within the input and output is an example of how to use the operator.

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In this example, I'm showing you the map operator.

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It's the same code we wrote in the previous lecture.

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The last component of a marble diagram are the marbles, the marbles or circles with values inside them

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on the first line.

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We are given an example of values that are pushed into the operator.

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The second line will show us the transformation applied to the values.

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In this case, we are pre seeing the dollar sign symbol.

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In some cases, if an operator can complete an observable, a vertical line will appear in the diagram.

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This line represents the completion of an observable.

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An X can appear on the diagram.

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This symbol represents an error not often used, but something you should know about.

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Marble diagrams can help us understand how an operator works by comparing the values from the input

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and output.

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They visualize the behavior of an operator for the rest of this course.

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We are going to review the behavior of an operator before writing code in the next lecture.

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We are going to continue exploring additional operators.