{ "componentChunkName": "component---src-templates-blog-post-js", "path": "/object-and-array-equality-in-javascript/", "result": {"data":{"markdownRemark":{"html":"
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Find out the difference between primitives and objects in JavaScript in my blog post here.
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Let's start by comparing some arrays and objects.

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[] === []; //false\n\n{} === {}; //false\n\n["apple"] === ["apple"]; //false\n\n{key: "value"} === {key: "value"}; //false
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The results are false because we are comparing two different instances of arrays and objects.

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Note: writing [] is the same as creating a new instance of Array and writing {} is the same as creating a new instance of Object.

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We can create a new array instance using new Array() and we can create a new object instance using new Object(). So, even if we change the arrays and objects examples in the previous example to the new syntax, we get the same result.

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new Array() === new Array() //false\n\nnew Object() === new Object() //false
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Object assignment

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const nums_array_one = [1, 2, 3, 4]\n\n// nums_array_two now points to nums_array_one\nconst nums_array_two = nums_array_one\n\nconsole.log(nums_array_one === nums_array_two) //true
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When we assigned the nums_array_two variable to nums_array_one, we did not create a copy of nums_array-one. nums_array_two simply created a reference to nums_array_one. In other words, nums_array_one & nums_array_two point to the same location in memory.

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This is why nums_array_one === nums_array_two is equal to true as we are comparing the same instance of the array.

\n","frontmatter":{"title":"Object & Array Equality in JavaScript","date":"2021-07-04"}}},"pageContext":{"slug":"/object-and-array-equality-in-javascript/","prev":{"fields":{"slug":"/response-json-in-JavaScript-fetch-api/"},"frontmatter":{"modules":null}},"next":{"fields":{"slug":"/when-and-how-to-use-functional-state-updates-in-react/"},"frontmatter":{"modules":null}}}}, "staticQueryHashes": ["3159585216"]}