Example 1: javascript remove duplicate in arrays
function removeDuplicates(array) {
return array.filter((a, b) => array.indexOf(a) === b)
};
function removeDuplicates(array) {
let x = {};
array.forEach(function(i) {
if(!x[i]) {
x[i] = true
}
})
return Object.keys(x)
};
function removeDuplicates(array) {
array.splice(0, array.length, ...(new Set(array)))
};
function removeDuplicates(array) {
let a = []
array.map(x =>
if(!a.includes(x) {
a.push(x)
})
return a
};
/THIS SITE/ "https://dev.to/mshin1995/back-to-basics-removing-duplicates-from-an-array-55he#comments"
Example 2: count duplicates array js
uniqueCount = ["a","b","c","d","d","e","a","b","c","f","g","h","h","h","e","a"];
var count = {};
uniqueCount.forEach(function(i) { count[i] = (count[i]||0) + 1;});
console.log(count);
Example 3: how to check for duplicate syntax in javascript
let strArray = [ "q", "w", "w", "w", "e", "i", "u", "r"];
let findDuplicates = arr => arr.filter((item, index) => arr.indexOf(item) != index)
console.log(findDuplicates(strArray))
console.log([...new Set(findDuplicates(strArray))])
Example 4: how to get duplicate values from array in javascript
var names = ['Mike', 'Matt', 'Nancy', 'Adam', 'Jenny', 'Nancy', 'Carl']
var uniq = names
.map((name) => {
return {
count: 1,
name: name
}
})
.reduce((a, b) => {
a[b.name] = (a[b.name] || 0) + b.count
return a
}, {})
var duplicates = Object.keys(uniq).filter((a) => uniq[a] > 1)
console.log(duplicates)
Example 5: js find duplicates in array
const names = ['Mike', 'Matt', 'Nancy', 'Adam', 'Jenny', 'Nancy', 'Carl']
const count = names =>
names.reduce((a, b) => ({ ...a,
[b]: (a[b] || 0) + 1
}), {})
const duplicates = dict =>
Object.keys(dict).filter((a) => dict[a] > 1)
console.log(count(names))
console.log(duplicates(count(names)))
Example 6: javascript check if array has duplicates
function hasDuplicates(array) {
return (new Set(array)).size !== array.length;
}