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Expressions and Operators

Expressions in JavaScript are formed from literal values, operators and the return values of function calls.

An example of an expression with two literals separated by an operator would be my_var = 4 + 5;.

Although it's not possible to multiply strings, JavaScript will try to convert expressions to an appropriate type. Therefore my_var = 4 * "5" is legal and will return the numeric value 20.

Operator Precedence

In common with other programming languages, JavaScipt gives precedence to multiplication and division over addition and subtraction etc.

Memorising and using the order of operator precedence usually leads to mistakes and unreadable code therefore the easiest way is to use parenthesis.

For example my_variable = 3 + 4 * 2; means that my_variable = 11;. However, my_variable = 3 + (4 * 2); is less error prone and much clearer.

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