125 lines
3.2 KiB
HTML
125 lines
3.2 KiB
HTML
<!DOCTYPE html>
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<html lang="en">
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<head>
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<meta charset="utf-8">
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<title>math.js | currency conversion</title>
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<script src="../../lib/browser/math.js"></script>
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<style>
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body,
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html,
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input {
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font-size: 11pt;
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font-family: verdana, arial, sans-serif;
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color: #4d4d4d;
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max-width: 600px;
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}
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h1 {
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font-size: 120%;
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}
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input {
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padding: 5px;
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width: 400px;
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}
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button {
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padding: 5px;
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}
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</style>
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</head>
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<body>
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<h1>Currency conversion with math.js</h1>
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<p>
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This example demonstrates how you can fetch actual currencies from <a href="https://fixer.io">fixer.io</a> and use them in math.js.
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</p>
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<p>
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Create a (free) account at <a href="https://fixer.io">fixer.io</a> and fill in your API access key below:
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</p>
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<form id="fetchForm">
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<input type="text" id="apiKey" placeholder="fixer.io API access key..." />
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<button type="submit" id="ok">Fetch currencies</button>
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</form>
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<p id="info">
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</p>
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<div id="form" style="display: none;">
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<p>
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<label for="expr">Enter an expression with currencies:</label>
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</p>
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<p>
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<input id="expr" value="5 EUR + 2 * 3 EUR in USD" /><br/>
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</p>
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<p id="result"></p>
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</div>
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<script>
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const accessKey = document.getElementById('apiKey')
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const fetchForm = document.getElementById('fetchForm')
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fetchForm.onsubmit = function (event) {
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event.preventDefault()
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document.getElementById('info').innerHTML = 'Fetching currencies...'
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fetchAndImportCurrencies(accessKey.value)
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.then(function (currencies) {
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document.getElementById('expr').oninput = evaluate
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document.getElementById('form').style.display = ''
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document.getElementById('info').innerHTML = 'Available currencies: ' + currencies.join(', ')
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evaluate()
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})
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.catch(function (err) {
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console.error(err)
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document.getElementById('info').innerHTML = '<span style="color: red;">' + err.toString() + '</span>'
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})
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}
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function fetchAndImportCurrencies (accessKey) {
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// fetch actual currency conversion rates
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return fetch('http://data.fixer.io/api/latest?access_key=' + accessKey)
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.then(function (response) {
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return response.json()
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})
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.then(function (data) {
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if (data.success) {
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// import the currencies
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math.createUnit(data.base)
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Object.keys(data.rates)
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.filter(function (currency) {
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return currency !== data.base
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})
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.forEach(function (currency) {
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math.createUnit(currency, math.unit(1 / data.rates[currency], data.base))
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})
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// return an array with all available currencies
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return Object.keys(data.rates).concat(data.base)
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}
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else {
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throw new Error(data.error.info)
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}
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})
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}
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function evaluate () {
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const expr = document.getElementById('expr')
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const result = document.getElementById('result')
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try {
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const resultStr = math.format(math.evaluate(expr.value), {notation: 'fixed', precision: 2})
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result.innerHTML = '<span style="color: dodgerblue;">' + resultStr + '</span>'
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}
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catch (err) {
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result.innerHTML = '<span style="color: red;">' + err.toString() + '</span>'
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}
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}
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</script>
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</body>
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</html> |