What judgment structures does JavaScript have?

Judgment structure: 1. if conditional branch structure, including if, "if else", "if else if ...", "if else if ... else" statements; 2. "switch case" conditional branch structure; 3. Ternary operation structure, syntax "Condition? Expression 1: Expression 2".

The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.

The branch structure is our common judgment structure, which determines whether to execute certain code programs based on the conditions set by the user. Below, Xiaoqian will introduce to you three common branch structure syntaxes.

IF conditional branch structure

if statement

Determine whether to execute the code through an if statementa

Syntax: if (condition) {code to be executed}

Determine whether the code inside {} is executed by whether the condition in () is true

if else statement

Use the if condition to determine which code in {} to execute

Syntax: if (condition) {Execute when the condition is true} else { Executed when the condition is false}

One of the two codes within {} must be executed

if else if ... statement

You can set multiple conditions for judgment through if and else if

Syntax: if (condition 1) {execute when condition 1 is true} else if (condition 2) {condition 2 is true executed}

If the first condition is true, then the content in the following {} will be executed

If the first condition is false, then the second condition will be judged conditions, and so on

For multiple {}, only one will be executed. Once one condition is true, the following conditions will no longer be judged

if else if ... else statement

is basically the same as the previous if else if ..., except that when all conditions are not met, the {} after the last else is executed

SWITCH conditional branch structure

is also a type of conditional judgment statement, which is a judgment on a certain variable

Syntax:

Use when you want to judge that a certain variable is equal to a certain value

Example: Display the day of the week based on the number given by the variable

Ternary operation (expanded)

Ternary operation is to use two symbols to form a statement

Ternary operation is just a shorthand form of if else statement

Grammar: Condition? Condition Execute when the condition is true: Execute when the condition is false

[Recommended learning: javascript advanced tutorial]

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