JS Basic: By value versus By reference
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The document discusses the differences between passing values by value versus by reference in JavaScript. It explains that primitive types like numbers and strings are compared by value, so two primitive values are equal only if they have the same value. In contrast, object types like arrays and objects are compared by reference, so two object references are equal only if they refer to the same object. The document provides examples of comparing values and references, as well as cloning objects to make copies. It also includes two quizzes, one to write a function to compare two strings, and another to clone an array value.
![Quiz2 Array Clone
ÕˆÑ}Ñu const DC = ['Batman', 'Jocker', 'Flash', 'SuperGirl']
DC_copy.push(¡®Arrow') //ÔÚÑ}ÑuµÄê‡ÁÐ push ?‚€ÐÂÖµ
console.log(DC,DC_copy) // Ó¡ÔÚ console](https://image.slidesharecdn.com/byvalueversusbyreference-170310033218/85/JS-Basic-By-value-versus-By-reference-13-320.jpg)
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JS Basic: By value versus By reference
- 1. JS Basic:? By Value V.S ? By Reference Leeboy @ goodideas-studio? 2017.03.10
- 2. Primitive type(1/6) Booleans Number String undefined null compare by value ?ÖµÏà±È Ö»ÓÐÔÚ¾ßÓÐÏàͬµÄÖµ£¬ƒÉÕß²ÅÏàµÈ Pass by value (e.g 1) Copy by value (e.g 2)
- 3. Primitive type(2/6) e.g.1 Pass by value
- 4. Primitive type(3/6) e.g.2 Copy by value
- 5. Primitive type(4/6) String - ²»¿É׃µÄ£¨immutable£©(e.g 3) - éL¶ÈÏàµÈ£¬Ë÷ÒýλÖÃ×ÖÔªÏàµÈ ?Quiz - Are strings compared by value or by reference?
- 9. Objective type(1/4) Object Function Array Set mutable compare (e.g1)(e.g 2) ‚€„eÎï¼þÓÀ²»ÏàµÈ ‚€„eê‡ÁÐÓÀ²»ÏàµÈ clone ÈçºÎÑ}Ñu (e.g3)(?quiz)
- 10. Objective type(2/4) e.g.1 Compare by reference Two references to distinct values are not equal, even if the two values consist of the same bytes.
- 11. Objective type(3/4) e.g.2 Compare by reference Two references are compared to see if they refer to the same value.
- 12. Objective type(4/4) e.g.3 Object Clone
- 13. Quiz2 Array Clone ÕˆÑ}Ñu const DC = ['Batman', 'Jocker', 'Flash', 'SuperGirl'] DC_copy.push(¡®Arrow') //ÔÚÑ}ÑuµÄê‡ÁÐ push ?‚€ÐÂÖµ console.log(DC,DC_copy) // Ó¡ÔÚ console