jkithome/inverted-index

Project files for the `Inverted Index` Javascript checkpoint

inverted-index

Running the checkpoint.

For security reasons Javascript cannot load local files in chrome. Therefore, we need to make the file containing the checkpoint a webserver. To do this I used local web server a node js package that can be found at https://www.npmjs.com/package/local-web-server. Once installed, run ws at the folder you want to serve.

Module explanation.

createIndex: It uses jQuery's getJSON mehod(used to get JSON data using an AJAX HTTP GET request) to read the book.json file. It then returns the data which should be an array containing objects.

getIndex: It takes the data obtained by createIndex as an argument. THe data returned is in form of an array. It loops through the array to obtain its contents(objects). It then obtains the keys of the object using Object.keys(object) method which ouputs an array. After this, it loops through the array using each key to access the particular object's value which is a string. The strings are split into individual words which are added to an array. Duplicate words are removed and the array sorted. Next, the words are compared to the contents of a stoplist array that contains english words not very important to the context such as a, an, the and at. Words not in the stoplist are put in an array contain the final words to be indexed. Finally, we loop through this array of words comparing them to the contents of the array read from the json file and then add the word as a key in an object and the index of the containing object as its value. Since there weren't occurences of words in both objects, if the key already exists in the object, the word is ignored. If it doesn't a new key is created. getIndex then creates a prototype dataIndex of the class Index and assigns it the object containing the indexed words.

searchIndex: It takes arguements either as an array of words or several strings and searches for them in dataIndex then returns an array containing the values that point to the location of the object(in the json data array) containing the word searched for. If the word isn't present, it returns -1.