simonh24 · simonh24 · Apr 15, 2020
diff --git a/index.js b/index.js
@@ -3,10 +3,10 @@
 // 🏡 Task 1: Variables
 /* Create variables for principal, interest rate, and years. Assign them the values 200000, 0.05, and 30 respectively. Create another value called name and give it the value of your own name.
 */
-
-
-
-
+let principal = 200000;
+let interest = 0.05;
+let years = 30;
+const name = "Simon Huang";
 
 // 🏡 Task 1.5: Simple Math
 /* To create a monthly mortgage rate calculator, we need to know the number of years in months and the monthly interest rate. 
@@ -15,8 +15,8 @@ Create a variable called `monthlyInterestRate` and give it the value of interest
 
 Create another variable called `periods` and give it the value of years*12.
 */
-
-
+let monthlyInterestRate = interest / 12;
+let periods = years * 12;
 
 
 // 🏡 Task 2: Harder Math
@@ -25,10 +25,13 @@ Create another variable called `periods` and give it the value of years*12.
 Hint: while these calculations can be done in one line, it might be helpful to create a variable called "numerator" to calculate the numerator, and another called "denominator" to calculate the denominator 
 
 Hint #2: you'll need to use the `math` object for parts of this calculation!
-
+,
 When your math is correct, monthlyRate will equal 1073.64
 */
-
+const numerator = Math.pow((monthlyInterestRate + 1), periods) * monthlyInterestRate;
+const denominator = Math.pow((1 + monthlyInterestRate), periods) - 1;
+const monthlyRate = principal * (numerator / denominator);
+console.log(monthlyRate);
 
 
 
@@ -37,7 +40,9 @@ When your math is correct, monthlyRate will equal 1073.64
 
 If your name is `Oscar` mortgageCalculator() should return "Oscar, your monthly rate is 1073.64"
 */
-
+function mortgageCalculator() {
+    return name + ", your monthly rate is " + monthlyRate;
+}
 
 
 
@@ -48,7 +53,18 @@ If your name is `Oscar` mortgageCalculator() should return "Oscar, your monthly
 For example,
 mortgageCalculator(2000000, 0.05, 30); <-- should return 1,073.64
 */
-
+function mortgageCalc(p, i, n, creditScore) {
+    if (creditScore > 740) {
+        i -= 0.005;
+    } else if (creditScore < 660) {
+        i += 0.005;
+    }
+    let monthlyInterest = i / 12;
+    let period = n * 12;
+    const num = Math.pow((monthlyInterest + 1), period) * monthlyInterest;
+    const denom = Math.pow((1 + monthlyInterest), period) - 1;
+    return (p * (num/denom));
+}
 
 
 
@@ -78,20 +94,66 @@ For example, variableInterestRate(200000, 0.04, 30) should console.log:
 "{Name}, with an interest rate of 0.06, your monthly rate is $1199"
 */
 
-
+function variableInterestRate(p, i, n) {
+    i -= 0.02;
+    for (let j = 0; j < 9; j++) {
+        let monthlyInterest = i / 12;
+        let period = n * 12;
+        const num = Math.pow((monthlyInterest + 1), period) * monthlyInterest;
+        const denom = Math.pow((1 + monthlyInterest), period) - 1;
+        console.log(name + ", with an interet rate of " + i.toFixed(3) + ", your monthly rate is $" + Math.round((p * (num/denom))));
+        i += 0.005;
+    }
+}
 
 
 // 🌟🌟🌟 STRETCH 🌟🌟🌟//
 
 /* Attempt any of the stretch goals below once you have finished the work above. Remember as always, these may require additional research beyond what you learned today */
 
 /*  🏡 Add  `Property Tax`, `Homeowner's insurance` and `HOA fees` as parameters in your function to calculate total monthly spending on housing */
-
+function stretchOne(p, i, n, propTaxRate, insurance, fees) {
+    let monthlyInterest = i / 12;
+    let period = n * 12;
+    let propTax = p * propTaxRate / 12; // principal * prop tax percent / 12 months for monthly
+    insurance = insurance / 12; // for monthly
+    // assuming hoa fees are monthly.
+    // also assuming principal is total cost, since no down payment or percentage given.
+    const num = Math.pow((monthlyInterest + 1), period) * monthlyInterest;
+    const denom = Math.pow((1 + monthlyInterest), period) - 1;
+    const mortgage = p * num / denom;
+    return mortgage + propTax + insurance + fees;
+    // unsure if calculations are correct.
+}
 
 /* 🏡 Build a calculator function that accepts `monthly payment` and `interest rate` and returns the maximum loan that a person could afford */
-
+function stretchTwo(monthly, interest, period) {
+    period *= 12; // assuming input is years.
+    // assuming interest inputted is decimal, eg. 0.05
+    for (let i = 0; i < period; i++) {
+        monthly = monthly * (1 + interest);
+    }
+    return monthly;
+    // unsure if calculations are correct.
+}
 
 /* 🏡 Explore using `window.prompt()` to allow a user to input parameters in the browser */
-
+function promptInterestRate() {
+    let p = window.prompt("Enter your principal");
+    let monthlyInterest = window.prompt("Enter your annual interest rate") / 12;
+    let period = window.prompt("Enter the amount of years") * 12;
+    const num = Math.pow((monthlyInterest + 1), period) * monthlyInterest;
+    const denom = Math.pow((1 + monthlyInterest), period) - 1;
+    return (p * (num/denom));
+}
 
 /* 🏡  Refactor your `variableInterestRate()` function to accept an array of interest rates (make sure to copy and paste as to not lose your work!) */
+function variableInterestRateArray(p, i, n) {
+    for (let j = 0; j < i.length; j++) {
+        let monthlyInterest = i[j] / 12;
+        let period = n * 12;
+        const num = Math.pow((monthlyInterest + 1), period) * monthlyInterest;
+        const denom = Math.pow((1 + monthlyInterest), period) - 1;
+        console.log(name + ", with an interet rate of " + i[j].toFixed(3) + ", your monthly rate is $" + Math.round((p * (num/denom))));
+    }
+}