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Implementation of Native JavaScript Methods (forEach, Map, Filter, Reduce, Every, Some)
'use strict';
/*****************NATIVE forEACH*********************/
Array.prototype.myEach = function(callback) {
for (var i = 0; i < this.length; i++)
callback(this[i], i, this);
};
//tests
var arr = ['biggy smalls', 'bif tannin', 'boo radley', 'hans gruber'];
arr.myEach(function(word) {
console.log(word);
});
//biggy smalls
//bif tannin
//boo radley
//hans gruber
/*****************NATIVE MAP*************************/
Array.prototype.myMap = function(callback) {
arr = [];
for (var i = 0; i < this.length; i++)
arr.push(callback(this[i], i, this));
return arr;
};
//tests
var arrs = ['dic tanin', 'boo radley', 'hans gruber'];
var numbers2 = [1, 4, 9];
var goodT = arrs.myMap(function(n) {
return n;
});
var squareRoot = numbers2.myMap(function(num) {
return Math.sqrt(num);
});
console.log(goodT); // [ 'dic tanin', 'boo radley', 'hans gruber' ]
console.log(squareRoot); // [ 1, 2, 3 ]
/*****************NATIVE FILTER*************************/
Array.prototype.myFilter = function(callback, context) {
arr = [];
for (var i = 0; i < this.length; i++) {
if (callback.call(context, this[i], i, this))
arr.push(this[i]);
}
return arr;
};
//tests
var numbers = [1, 20, 30, 80, 2, 9, 3];
var newNum = numbers.myFilter(function(n) {
return n >= 10;
});
console.log(newNum); // [ 20, 30, 80 ]
/*****************NATIVE REDUCE*************************/
Array.prototype.myReduce = function(callback, initialVal) {
var accumulator = (initialVal === undefined) ? undefined : initialVal;
for (var i = 0; i < this.length; i++) {
if (accumulator !== undefined)
accumulator = callback.call(undefined, accumulator, this[i], i, this);
else
accumulator = this[i];
}
return accumulator;
};
//tests
var numbers3 = [20, 20, 2, 3];
var total = numbers3.myReduce(function(a, b) {
return a + b;
}, 10);
console.log(total); // 55
var flattened = [
[0, 1],
[2, 3],
[4, 5]
].reduce(function(a, b) {
return a.concat(b);
});
console.log(flattened); //[ 0, 1, 2, 3, 4, 5 ]
/*****************NATIVE EVERY*************************/
Array.prototype.myEvery = function(callback, context) {
for (var i = 0; i < this.length; i++) {
if (!callback.call(context, this[i], i, this))
return false;
}
return true;
};
//tests
var passed = [12, 5, 8, 130, 44].myEvery(function(element) {
return (element >= 10);
});
console.log(passed); // false
passed = [12, 54, 18, 130, 44].myEvery(function(element) {
return (element >= 10);
});
console.log(passed); // true
passed = [12, 54, 18, 130, 44].myEvery(function(element) {
return (element >= 13);
});
console.log(passed); // false
/*****************NATIVE SOME*************************/
Array.prototype.mySome = function(callback, context) {
for (var i = 0; i < this.length; i++) {
if (callback.call(context, this[i], i, this))
return true;
}
return false;
};
//tests
var passed = [12, 5, 8, 130, 44].mySome(function(element) {
return (element >= 200);
});
console.log('some: ' + passed); //some: false
var passed = [12, 5, 8, 130, 44].mySome(function(element) {
return (element >= 100);
});
console.log('some: ' + passed); //some: true
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