finished array helpers

Author: enuber

app/index.js

@@ -14,7 +14,7 @@ colors.forEach(function(color) {
 
 var numbers = [1,2,3,4,5];
 
-//Create a variabl to hold the sum
+//Create a variable to hold the sum
 
 var sum = 0;
 
@@ -76,7 +76,7 @@ var products = [
     { name: 'banana', type: 'fruit', quantity: 3, price: 5}
 ];
 
-var filteredProducts = []
+var filteredProducts = [];
 
 for (var i=0; i < products.length; i++) {
     if (products[i].type === 'fruit') {
@@ -114,3 +114,191 @@ function commentsForPost(post, comments) {
 
 console.log(commentsForPost(post, comments));
 
+/** find **/
+
+var users = [
+    { name: 'jill'},
+    { name: 'alex' },
+    { name: 'bill' }
+];
+
+var user;
+
+for (var i=0; i < users.length; i++) {
+    if (users[i].name === 'alex'){
+        user = users[i];
+        break;
+    }
+}
+
+console.log(user);
+
+var userFound = users.find(function(user) {  //will return only the first time it is found
+    return user.name === "alex";
+});
+
+console.log(userFound);
+
+function Car(model){
+    this.model = model;
+}
+
+var cars = [
+    new Car('Buick'),
+    new Car('Camaro'),
+    new Car('Focus')
+];
+
+var carFound = cars.find(function(car) {
+    return car.model === 'Focus';
+});
+console.log(carFound);
+
+var posts = [
+    { id: 1, title: "new post"},
+    { id: 2, title: 'old post'}
+];
+
+var comment = { postId: 1, content: 'Great Post'};
+
+function postForComment(posts, comment) {
+    return posts.find(function(post){
+        return post.id === comment.postId;
+    })
+}
+
+console.log(postForComment(posts, comment));
+
+//every and some
+//with every we can view it as an && operator between each item in an array and
+//with some we can view it as an || operator between each item
+
+
+var computers = [
+    { name: 'Apple', ram: 24},
+    { name: 'Compaq', ram: 4 },
+    { name: 'Acer', ram: 32 }
+];
+
+var allComputerCanRunProgram = true;
+
+var onlySomeCanRunProgram = false;
+
+for (var i=0; i<computers.length; i++) {
+    var computer = computers[i];
+
+    if (computer.ram < 16) {
+        allComputerCanRunProgram = false;
+    } else {
+        onlySomeCanRunProgram = true;
+    }
+}
+
+console.log('all: ', allComputerCanRunProgram);
+console.log('some: ', onlySomeCanRunProgram);
+
+var arrEvery = computers.every(function(computer) {
+    return computer.ram > 16;
+});
+
+var arrSome = computers.some(function(computer) {
+    return computer.ram > 16;
+});
+
+console.log('every: ', arrEvery);
+console.log('some: ', arrSome);
+
+var names = [
+    'Alexandria',
+    'Matthew',
+    'Joe'
+];
+
+var namesEvery = names.every(function(name){
+    return name.length > 4;
+});
+
+var namesSome = names.some(function(name){
+    return name.length > 4;
+});
+
+console.log('every: ', namesEvery);
+console.log('some: ', namesSome);
+
+function Field(value) {
+    this.value = value;
+}
+
+Field.prototype.validate = function() {
+    return this.value.length > 0;
+}
+
+var username = new Field('2cool');
+var password = new Field('my_password');
+var birthdate = new Field('10/10/2010');
+
+
+var isValid = username.validate() && password.validate() && birthdate.validate();
+
+console.log('validate: ', isValid);
+
+var fields = [username, password, birthdate];
+
+//this keeps it cleaner and more simple than declaring the variable above isValid and doing && statements for everything
+var formIsValid = fields.every(function(field) {
+    return field.validate();
+});
+
+if (formIsValid) {
+    //allow user to submit!
+} else {
+    //show an error msg
+}
+
+//Reduce
+
+var numbersArr = [10, 20, 30];
+
+var sumArr = 0;
+
+for (var i = 0; i < numbersArr.length; i++) {
+    sumArr += numbersArr[i];
+}
+console.log(sumArr);
+
+
+// here 0 is being passed in as the initial value, so 0 could be any starting value you want. It is coming into the
+//function as what "sum" is here. number is the individual number in each step through the numbersArr
+var reduceArr = numbersArr.reduce(function(sum, number) {
+    return sum + number;
+}, 0);
+
+console.log('reduced array: ', reduceArr);
+
+var primaryColors = [
+    { color: 'red' },
+    { color: 'yellow' },
+    { color: 'blue' }
+];
+
+var justColors = primaryColors.reduce(function(previous, primaryColor) {
+    previous.push(primaryColor.color);
+    return previous;
+}, []);
+
+console.log('colors: ', justColors);
+
+
+//without the ! we would just get a count of numbers by adding in the ! we are saying we want a boolean and
+//0 = true every other number else is = false so this will work for our case. the final return statement here
+// will still returnthe counter if anything other than a parenthesis is found
+function balancedParens(string) {
+    return !string.split('').reduce(function(counter, char) {
+        if (counter < 0) {return counter}  //this catches the case of )( where they still balance but not properly
+        if (char === '(') { return ++counter} //adds a 1 if open
+        if (char === ')') { return --counter} //decreases by 1 if closing
+        return counter; //if anything else is encountered we return the counter and ignore it
+    }, 0);
+}
+
+balancedParens('((((');