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218 changes: 196 additions & 22 deletions package-lock.json

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3 changes: 2 additions & 1 deletion package.json
Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,7 @@
"regenerator-runtime": "^0.10.3"
},
"dependencies": {
"eslint-config-airbnb": "^14.1.0"
"eslint-config-airbnb": "^14.1.0",
"lint": "^1.1.2"
}
}
40 changes: 38 additions & 2 deletions src/arrays.js
Original file line number Diff line number Diff line change
Expand Up @@ -14,12 +14,20 @@ const each = (elements, cb) => {
// This only needs to work with arrays.
// You should also pass the index into `cb` as the second argument
// based off http://underscorejs.org/#each
for (let i = 0; i <= elements.length - 1; i++) {
cb(elements[i], i);
}
};

const map = (elements, cb) => {
// Do NOT use .map, to complete this function.
// Produces a new array of values by mapping each value in list through a transformation function (iteratee).
// Return the new array.
const newArray = [];
for (let i = 0; i < elements.length; i++) {
newArray.push(cb(elements[i]));
}
return newArray;
};

const reduce = (elements, cb, startingValue) => {
Expand All @@ -28,26 +36,54 @@ const reduce = (elements, cb, startingValue) => {
// Elements will be passed one by one into `cb` along with the `startingValue`.
// `startingValue` should be the first argument passed to `cb` and the array element should be the second argument.
// `startingValue` is the starting value. If `startingValue` is undefined then make `elements[0]` the initial value.
// const someArray = [];

// for (let i = 0; i <= elements.length; i++) {

// }

// cb(startingValue, someArray);
let i = 0;
if (startingValue === undefined) {
startingValue = elements[0];
i = 1;
}
for (; i < elements.length; i++) {
startingValue = cb(startingValue, elements[i]);
}
return startingValue;
};

const find = (elements, cb) => {
// Do NOT use .includes, to complete this function.
// Look through each value in `elements` and pass each element to `cb`.
// If `cb` returns `true` then return that element.
// Return `undefined` if no elements pass the truth test.
for (let i = 0; i < elements.length; i++) {
if (cb(elements[i]) === true) {
return elements[i];
}
}
};

const filter = (elements, cb) => {
// Do NOT use .filter, to complete this function.
// Similar to `find` but you will return an array of all elements that passed the truth test
// Return an empty array if no elements pass the truth test
const filtrue = [];
for (let i = 0; i < elements.length; i++) {
if (cb(elements[i]) === true) {
return filtrue.push(elements[i]);
}
return filtrue;
}
};

/* STRETCH PROBLEM */

const flatten = (elements) => {
// Flattens a nested array (the nesting can be to any depth).
// Example: flatten([1, [2], [3, [[4]]]]); => [1, 2, 3, 4];
// Flattens a nested array (the nesting can be to any depth).
// Example: flatten([1, [2], [3, [[4]]]]); => [1, 2, 3, 4];
};

/* eslint-enable no-unused-vars, max-len */
Expand Down
10 changes: 10 additions & 0 deletions src/callbacks.js
Original file line number Diff line number Diff line change
@@ -1,26 +1,36 @@
const firstItem = (arr, cb) => {
// firstItem passes the first item of the given array to the callback function.
cb(arr[0]);
};

const getLength = (arr, cb) => {
// getLength passes the length of the array into the callback.
cb(arr.length);
};

const last = (arr, cb) => {
// last passes the last item of the array into the callback.
cb(arr[arr.length - 1]);
};

const sumNums = (x, y, cb) => {
// sumNums adds two numbers (x, y) and passes the result to the callback.
const sum = x + y;
return cb(sum);
};

const multiplyNums = (x, y, cb) => {
// multiplyNums multiplies two numbers and passes the result to the callback.
const sum = x * y;
return cb(sum);
};

const contains = (item, list, cb) => {
// contains checks if an item is present inside of the given array/list.
// Pass true to the callback if it is, otherwise pass false.
if (list.includes(item)) {
return cb(true);
} return cb(false);
};

/* STRETCH PROBLEM */
Expand Down
23 changes: 23 additions & 0 deletions src/closure.js
Original file line number Diff line number Diff line change
Expand Up @@ -5,17 +5,40 @@ const counter = () => {
// Example: const newCounter = counter();
// newCounter(); // 1
// newCounter(); // 2
let count = 0;
return () => {
count++;
return count;
};
};

const counterFactory = () => {
// Return an object that has two methods called `increment` and `decrement`.
// `increment` should increment a counter variable in closure scope and return it.
// `decrement` should decrement the counter variable and return it.
let count = 0;
const newObj = {
increment: () => {
count++;
return count;
},
decrement: () => {
count--;
return count;
},
};
return newObj;
};

const limitFunctionCallCount = (cb, n) => {
// Should return a function that invokes `cb`.
// The returned function should only allow `cb` to be invoked `n` times.
let count = 0;
return (...blah) => {
count++;
if (count < n) return cb(...blah);
return null;
};
};

/* STRETCH PROBLEM */
Expand Down
13 changes: 13 additions & 0 deletions src/objects.js
Original file line number Diff line number Diff line change
Expand Up @@ -5,22 +5,35 @@ const keys = (obj) => {
// Retrieve all the names of the object's properties.
// Return the keys as strings in an array.
// Based on http://underscorejs.org/#keys
obj.key = Object.keys(obj);
return obj.key;
};

const values = (obj) => {
// Return all of the values of the object's own properties.
// Ignore functions
// http://underscorejs.org/#values
obj.value = Object.values(obj);
return obj.value;
};

const mapObject = (obj, cb) => {
// Like map for arrays, but for objects. Transform the value of each property in turn.
// http://underscorejs.org/#mapObject
// const keyThing = Object.keys(obj);
// keyThing.map(key => obj[keyThing] = cb(obj[keyThing]));
// return obj;
const objKeys = Object.keys(obj);
for (let i = 0; i < objKeys.length; i++) {
obj[objKeys[i]] = cb(obj[objKeys[i]]);
}
return obj;
};

const pairs = (obj) => {
// Convert an object into a list of [key, value] pairs.
// http://underscorejs.org/#pairs
return Object.keys(obj).map(key => [key, obj[key]]);
};

/* STRETCH PROBLEMS */
Expand Down
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