forked from ii0/readnote
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy path01_javascript_demo.html
More file actions
252 lines (222 loc) · 6.1 KB
/
Copy path01_javascript_demo.html
File metadata and controls
252 lines (222 loc) · 6.1 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
<!DOCTYPE html>
<html>
<head>
<title>JavaScipt Loan Calculator</title>
<style type="text/css">
.output {font-family: bold;}
#payment {text-decoration: underline;}
#graph {border: solid black 1px;}
th, td {vertical-align: top;}
</style>
</head>
<body>
<table>
<tr>
<th>Enter Loan Data:</th>
<th></th>
<th>Loan Balance, Cumulative Equity, and Interest Payments</th>
</tr>
<tr>
<td>Amount of the loan ($):</td>
<td><input id="amount" onchange="calculate();"></td>
<td rowspan=8><canvas id="graph" width="400" height="250"></canvas></td>
</tr>
<tr>
<td>
Annual interest (%):
</td>
<td>
<input id="apr" onchange="calculate();">
</td>
</tr>
<tr>
<td>
Repayment period (years):
</td>
<td>
<input id="years" onchange="calculate();" >
</td>
</tr>
<tr>
<td>Zipcode (to find letters)</td>
<td>
<input id="zipcode" onchange="calculate();">
</td>
</tr>
<tr>
<th>
Approximate Payments:
</th>
<td>
<button onclick="calculate();">Calculate</button>
</td>
</tr>
<tr>
<td>Monthly Payment:</td>
<td>
$<span class="output" id="payment"></span>
</td>
</tr>
<tr>
<td>Total Payment:</td>
<td>
$<span class="output" id="total"></span>
</td>
</tr>
<tr>
<td>Total interest:</td>
<td>
$<span class="output" id="totalinterest"></span>
</td>
</tr>
<tr>
<th>Sponsors:</th>
<td clospan=2>
Apply for your loan with one of these fine lenders:
<div id="lenders"></div>
</td>
</tr>
</table>
<script type="text/javascript">
"use strict";
window.onload = function(){
if (window.localStorage && localStorage.loan_amount){
document.getElementById("amount").value = localStorage.loan_amount;
document.getElementById("apr").value = localStorage.loan_apr;
document.getElementById("years").value = localStorage.loan_years;
document.getElementById("zipcode").value = localStorage.loan_zipcode;
}
};
function calculate(){
var amount = document.getElementById("amount");
var apr = document.getElementById("apr");
var years = document.getElementById("years");
var zipcode = document.getElementById("zipcode");
var payment = document.getElementById("payment");
var total = document.getElementById("total");
var totalinterest = document.getElementById("totalinterest");
var principal = parseFloat(amount.value);
var interest = parseFloat(apr.value) / 100 / 12;
var payments = parseFloat(years.value) * 12;
var x = Math.pow(1 + interest, payments);
var monthly = (principal * x * interest) / (x - 1);
if(isFinite(monthly)){
payment.innerHTML = monthly.toFixed(2);
total.innerHTML = (monthly * payments).toFixed(2);
totalinterest.innerHTML = ((monthly * payments) - principal).toFixed(2);
save(amount.value, apr.value, years.value, zipcode.value);
try{
getLenders(amount.value, apr.value, years.value, zipcode.value);
}
catch(e){
console.error(e);
}
chart(principal, interest, monthly, payments);
}
else{
payment.innerHTML = "";
total.innerHTML = "";
totalinterest.innerHTML = "";
chart();
}
}
function save(amount, apr, years, zipcode) {
if (window.localStorage){
localStorage.loan_amount = amount;
localStorage.loan_apr = apr;
localStorage.loan_years = years;
localStorage.loan_zipcode = zipcode;
}
}
function getLenders(amount, apr, years, zipcode){
if (!window.XMLHttpRequest) return;
var ad = document.getElementById("lenders");
if(!ad) return;
var url = "getLenders.php" +
"?amt=" + encodeURIComponent(amount) +
"&apr=" + encodeURIComponent(apr) +
"&yrs=" + encodeURIComponent(years) +
"&zip=" + encodeURIComponent(zipcode);
var req = new XMLHttpRequest();
req.open('GET', url);
console.log(url);
req.send(null);
req.onreadystatechange = function(){
if(req.readyState == 4 && req.readyState == 200){
var response = req.responseText;
var lenders = JSON.parse(response);
var list = "";
for (var i=0; i< lenders.length; i++){
list += "<li><a href='" + lenders[i].url + "'>" + lenders[i].name + "</a>";
}
ad.innerHTML = "<ul>" + list + "</ul>";
}
}
}
function chart(principal, interest, monthly, payments){
var graph = document.getElementById('graph');
graph.width =graph.width; // 用一种巧妙的手法清除并重置画布
if(arguments.length == 0 || !graph.getContext) return;
var g = graph.getContext("2d");
var width = graph.width, height = graph.height;
function paymentToX(n) {
return n * width / payments;
}
function amountToY(a) {
return height - (a * height / (monthly * payments * 1.05));
}
g.moveTo(paymentToX(0), amountToY(0));
g.lineTo(paymentToX(payments), amountToY(monthly * payments));
g.lineTo(paymentToX(payments), amountToY(0));
g.closePath();
g.fillStyle = "#f88";
g.fill();
g.font = "bold 12px sans-serif";
g.fillText("Total Interest Payments", 20, 20);
var equity = 0;
g.beginPath();
g.moveTo(paymentToX(0), amountToY(0));
for (var p = 1; p <= payments; p++){
var thisMonthsInterest = (principal - equity) * interest;
equity += (monthly - thisMonthsInterest);
g.lineTo(paymentToX(p), amountToY(equity));
}
g.lineTo(paymentToX(payments), amountToY(0));
g.closePath();
g.fillStyle = "green";
g.fill();
g.fillText("Total Equity", 20, 35);
var bal = principal;
g.beginPath();
g.moveTo(paymentToX(0), amountToY(bal));
for (var p = 1; p <= payments; p++){
var thisMonthsInterest = bal * interest;
bal -= (monthly - thisMonthsInterest);
g.lineTo(paymentToX(p), amountToY(bal));
}
g.lineWidth = 3;
g.stroke();
g.fillStyle = "black";
g.fillText("Loan Balance", 20, 50);
g.textAlign = "center";
var y = amountToY(0);
for (var year = 1; year * 12 <= payments; year++){
var x = paymentToX(year * 12);
g.fillRect(x - 0.5, y-3, 1, 3);
if (year ==1)g.fillText("Year", x, y-5);
if (year % 5 == 0 && year * 12 != payments)
g.fillText(String(year), x, y - 5 );
}
g.textAlign = "right";
g.textBaseline = "middle";
var ticks = [monthly * payments, principal];
var rightEdge = paymentToX(payments);
for (var i = 0; i < ticks.length; i++){
var y = amountToY(ticks[i]);
g.fillRect(rightEdge - 3, y - 0.5, 3, 1);
g.fillText(String(ticks[i].toFixed(0)), rightEdge - 5, y);
}
}
</script>
</body>
</html>