--- id: 587d78b2367417b2b2512b0f title: Remove Items from an Array with pop() and shift() challengeType: 1 forumTopicId: 301165 --- ## Description <section id='description'> Both <code>push()</code> and <code>unshift()</code> have corresponding methods that are nearly functional opposites: <code>pop()</code> and <code>shift()</code>. As you may have guessed by now, instead of adding, <code>pop()</code> <em>removes</em> an element from the end of an array, while <code>shift()</code> removes an element from the beginning. The key difference between <code>pop()</code> and <code>shift()</code> and their cousins <code>push()</code> and <code>unshift()</code>, is that neither method takes parameters, and each only allows an array to be modified by a single element at a time. Let's take a look: ```js let greetings = ['whats up?', 'hello', 'see ya!']; greetings.pop(); // now equals ['whats up?', 'hello'] greetings.shift(); // now equals ['hello'] ``` We can also return the value of the removed element with either method like this: ```js let popped = greetings.pop(); // returns 'hello' // greetings now equals [] ``` </section> ## Instructions <section id='instructions'> We have defined a function, <code>popShift</code>, which takes an array as an argument and returns a new array. Modify the function, using <code>pop()</code> and <code>shift()</code>, to remove the first and last elements of the argument array, and assign the removed elements to their corresponding variables, so that the returned array contains their values. </section> ## Tests <section id='tests'> ```yml tests: - text: <code>popShift(["challenge", "is", "not", "complete"])</code> should return <code>["challenge", "complete"]</code> testString: assert.deepEqual(popShift(['challenge', 'is', 'not', 'complete']), ["challenge", "complete"]); - text: The <code>popShift</code> function should utilize the <code>pop()</code> method testString: assert.notStrictEqual(popShift.toString().search(/\.pop\(/), -1); - text: The <code>popShift</code> function should utilize the <code>shift()</code> method testString: assert.notStrictEqual(popShift.toString().search(/\.shift\(/), -1); ``` </section> ## Challenge Seed <section id='challengeSeed'> <div id='js-seed'> ```js function popShift(arr) { let popped; // change this line let shifted; // change this line return [shifted, popped]; } // do not change code below this line console.log(popShift(['challenge', 'is', 'not', 'complete'])); ``` </div> </section> ## Solution <section id='solution'> ```js function popShift(arr) { let popped = arr.pop(); // change this line let shifted = arr.shift(); // change this line return [shifted, popped]; } ``` </section>