63 lines
2.5 KiB
Markdown
63 lines
2.5 KiB
Markdown
---
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title: Ternary Operator
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---
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The Ternary operator replaces an `if`/`else` block in a condensed format. It is also referred to as the conditional operator, inline if (iif), or ternary if. The following is the general format of the ternary operator.
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```
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condition ? expr1 : expr2
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```
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## Description
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If `condition` evaluates to true, the operator resolves to the value of `expr1`; otherwise, it resolves to the value of `expr2`.
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For example, to display a different message based on the value of the isMember variable, you can use the following statements:
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```javascript
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let isMember = true;
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let message = (isMember) ? 'Welcome Back!' : 'You need to login'; // 'Welcome Back'
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```
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 <a href='https://repl.it/M8Ge/1' target='_blank' rel='nofollow'>Run Code</a>
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## Running functions with ternary operator
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It's also possible to run functions using ternary operator, which sometimes can be useful and more readable.
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```javascript
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const runFirst = true;
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(runFirst) ? first() : second();
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```
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## Chaining using the ternary operator
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You can also chain a ternary operator indefinitely, in a similar way to using `else if's` before the final `else` of an an `if`/`else` block. Each time the colon is used to state the `else` part of the ternary operator a new condition can be stated until the final termination condition is used.
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```javascript
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function displayNum (num) {
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return num === 3 ? 'number is 3' : num === 2 ? 'number is 2' : num === 1 ? 'number is 1 ' : 'number is not in range';
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}
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```
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To ease readability, the code using ternary operators is often formatted across multiple lines as follows:
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```javascript
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function displayNum(num) {
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return num === 3
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? 'number is 3'
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: num === 2
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? 'number is 2'
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: num === 1
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? 'number is 1'
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: 'number is not in range';
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}
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```
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This way of using the ternary operator needs to be done sparingly and in the right places, which is why (as is the case with using multiple `else if's`), it can sometimes lead to more readable code by using a `switch` statement instead.
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It is advisable to use the ternary operator only in cases which include both `if` and `else` conditions, otherwise using an `if` block is recommended. Chaining ternary operators without care may cause unforeseen bugs.
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**Read more:** <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Conditional_Operator' target='_blank' rel='nofollow'>MDN</a>
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