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- ## Type Conversion - Number and String
- 1. The `+` operator when used as a unary operator always converts its operand to a `number`.
- 2. 2. Using the unary `+` operator on a value is functionally equivalent to casting the value using the `Number()` function.
- 1. `+new Date === Number(new Date); // true`
- ```javascript
- console.log(+'100'); // 100
- console.log(+null); // 0
- console.log(+void 0); // NaN
- console.log(+true); // 1
- console.log(+false); // 0
- console.log(+[]); // 0
- console.log(+[100]); // 100
- console.log(+[100, 50]); // NaN
- console.log(+{}); // NaN
- console.log(+new Date); // 1527790306576
- ```
- 1. The `+` operator can also be used to convert values to `string`. Concatenate an empty string(`''`) to any value using the `+` operator to convert the value to a `string`.
- 2. Using the `+` operator to convert values to `string` is functionally equivalent to casting values to string using the `String()` function.
- 1. `([100, 50] + '') === String([100, 50]); // true`
- ```javascript
- console.log(100 + ''); // "100"
- console.log(null + ''); // "null"
- console.log(void 0 + ''); // "undefined"
- console.log(true + ''); // "true"
- console.log(false + ''); // "false"
- console.log([] + ''); // ""
- console.log([100] + ''); // "100"
- console.log([100, 50] + ''); // "100,50"
- console.log({} + ''); // "[object Object]"
- console.log(new Date + ''); // "Thu May 31 2018 19:28:09 GMT+0100 (WAT)"
- ```
- ## Short-Circuiting
- 1. The logical `&&` short-circuiting is commonly used as a replacement for very simple `if` statements
- 2. *The logical `&&` operator returns the first operand if it is falsy, otherwise it returns the second operand.*
- ```javascript
- if (person) {
- fetchProfile(person);
- }
- // METHOD 2: Using short-circuiting
- person && fetchProfile(person);
- ```
- 1. Note that using short-circuiting actually returns a value since it is a JavaScript expression. Hence, the result of a short-circuiting operation can be stored in a variable or used anywhere JavaScript expects a value.
- ```javascript
- var personProfile = person && fetchProfile(person);
- ```
- 1. The logical `||` operator returns the first operand if it is `truthy`, otherwise it returns the second operand.
- 2. The logical `||` short-circuiting is commonly used when assigning fallback values to local variables
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