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Copy pathobjects.js
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95 lines (74 loc) · 2.46 KB
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// Complete the following underscore functions.
// Reference http://underscorejs.org/ for examples.
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
return Object.keys(obj);
};
const values = (obj) => {
// Return all of the values of the object's own properties.
// Ignore functions
// http://underscorejs.org/#values
return Object.values(obj);
};
const mapObject = (obj, cb) => {
// Like map for arrays, but for objects. Transform the value of each property in turn.
// http://underscorejs.org/#mapObject
const keysArr = keys(obj);
const valsArr = values(obj);
for (let i = 0; i < keysArr.length; i++) {
obj[keysArr[i]] = cb(valsArr[i]);
}
return obj;
};
const pairs = (obj) => {
// Convert an object into a list of [key, value] pairs.
// http://underscorejs.org/#pairs
const resultArr = [];
const keysArr = keys(obj);
const valsArr = values(obj);
for (let i = 0; i < keysArr.length; i++) {
resultArr[i] = [keysArr[i], valsArr[i]];
}
return resultArr;
};
/* STRETCH PROBLEMS */
const invert = (obj) => {
// Returns a copy of the object where the keys have become the values and the values the keys.
// Assume that all of the object's values will be unique and string serializable.
// http://underscorejs.org/#invert
// Create new object to return
const newObj = {};
// Loop through obj and for each pair insert them into newObj in reverse order
Object.entries(obj).forEach(pair => newObj[pair[1]] = pair[0]);
// return newly reversed object
return newObj;
};
const defaults = (obj, defaultProps) => {
// Fill in undefined properties that match properties on the `defaultProps` parameter object.
// Return `obj`.
// http://underscorejs.org/#defaults
// Create copy of obj to manipulate
const returnObj = Object.assign({}, obj);
// Create variable for quick reference
const defProps = keys(defaultProps);
// Loop through keys of defaultProps and compare to keys of returnObj
for (let i = 0; i < defProps.length; i++) {
if (!keys(returnObj).includes(defProps[i])) { // If no matching key is found
// Add key and value to returnObj
returnObj[defProps[i]] = defaultProps[defProps[i]];
}
}
// Return obj with newly added defaults
return returnObj;
};
/* eslint-enable no-unused-vars */
module.exports = {
keys,
values,
mapObject,
pairs,
invert,
defaults,
};