Looping through objects in javascript

In this post I will explain you the various methods to loop through objects in javascript programming language.

for . . . in

• This approach is used to loop through the keys of an object
• By looping through the keys, you can get the value using object[key]

const object = { name: "Dhanush", language:"js" } for(const key in object){ const value = object[key] console.log("Key: ",key) console.log("Value: ",value) } // Key: name // Value: Dhanush // Key: language // Value: js 

Object.keys()

• The keys method of the Object constructor returns an array of the keys in an object
• With the array of keys you can then loop through the array using any array approaches.
• You can get the value fo the objects key also using object[key]

const object = { name: "Dhanush", language:"js" } const keys = Object.keys(object) // ['name', 'language'] keys.forEach(function(key){ const value = object[key] console.log("Key: ",key) console.log("Value: ",value) }) // Key: name // Value: Dhanush // Key: language // Value: js 

Object.values()

• The values method returns an array of the values in an object ( opposite to keys method )
• With the array got you can loop through them using any array functionality
• You can use a key to get a value directly but you cannot use a value to get a key directly

const object = { name: "Dhanush", language:"js" } const values = Object.values(object) // ['Dhanush', 'js'] values.forEach(function(value){ console.log(value) }) // Dhanush // js 

Object.entries()

• The entries method returns an array of subarrays where each subarray has two items, the first one being the key and the second one being the value
• Unlike the keys and values method, entries returns the keys and values of an object in subarrays.
• Then you can access them using the index.

const object = { name: "Dhanush", language:"js" } const entries = Object.entries(object) // [ // ['name', 'Dhanush'], // ['language', 'js'], // ] entries.forEach(function(entry){ const key = entry[0] const value = entry[1] console.log("Key: ",key) console.log("Value: ",value) console.log(value) }) // Key: name // Value: Dhanush // Key: language // Value: js 

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