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si.js
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si.js
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/*!
si-tools
Parsing and formatting of SI numbers SI.format(0.000005, 'M') → '5µM'
https://github.com/stereosteve/si-tools
forked from https://github.com/sindresorhus/pretty-bytes
by Steve Perkins, Sindre Sorhus
MIT License
*/
(function () {
'use strict';
// Number.isNaN() polyfill
var isNaN = function (val) {
return val !== val;
};
var isNumeric = function isNumber(n) {
return !isNaN(parseFloat(n)) && isFinite(n);
};
// String trim polyfill
if (!String.prototype.trim) {
(function(){
// Make sure we trim BOM and NBSP
var rtrim = /^[\s\uFEFF\xA0]+|[\s\uFEFF\xA0]+$/g;
String.prototype.trim = function () {
return this.replace(rtrim, '');
};
})();
}
var exponentTable = {
8: 'Y', // yotta
7: 'Z', // zetta
6: 'E', // exa
5: 'P', // peta
4: 'T', // tera
3: 'G', // giga
2: 'M', // mega
1: 'k', // kilo
0: '',
'-1': 'm', // milli
'-2': 'µ', // micro
'-3': 'n', // nano
'-4': 'p', // pico
'-5': 'f', // femto
'-6': 'a', // atto
'-7': 'z', // zepto
'-8': 'y' // ycoto
};
var prefixTable = {};
for (var exp in exponentTable) {
if (exponentTable.hasOwnProperty(exp)) {
var prefix = exponentTable[exp];
if (prefix.length === 0) {
continue;
}
prefixTable[prefix] = exp;
}
}
var aliasTable = {
'u': 'µ',
'K': 'k'
};
var key, alias;
for (alias in aliasTable) {
key = aliasTable[alias];
prefixTable[alias] = prefixTable[key];
}
var allPrefixes = '';
for (key in prefixTable) {
allPrefixes += key;
}
var parseRegex = new RegExp('^([\-0-9.eE]+) ?([' + allPrefixes + '])?(.*)');
var SI = {};
SI.compute = function (num) {
if (typeof num !== 'number') num = parseFloat(num);
if (isNaN(num)) throw new TypeError('si-tools: input must be a number');
var input = num;
var exponent;
var prefix;
var neg = num < 0;
if (neg) {
num = -num;
}
if (num === 0) {
return {
input: input,
number: num,
prefix: ''
};
}
exponent = Math.floor(Math.log(num) / Math.log(1000));
prefix = exponentTable[exponent];
num = (num / Math.pow(1000, exponent));
if (neg) {
num *= -1;
}
return {
input: input,
number: num,
prefix: prefix
};
};
SI.format = function (number, unit, separator, precision) {
var si = SI.compute(number);
if (!isNumeric(precision)) precision = 5;
var parts = [
si.number.toFixed(precision).replace(/\.?0+$/, ''),
separator,
si.prefix,
unit
];
var str = parts.join('');
return str;
};
SI.parse = function(str) {
var num, prefix, unit;
var m = parseRegex.exec(str);
if (m) {
num = parseFloat(m[1]);
prefix = m[2];
unit = m[3];
}
var exp = prefixTable[prefix];
if (exp) {
num = num * Math.pow(1000, exp);
}
// if alias, use the proper prefix
if (prefix && aliasTable[prefix]) {
prefix = aliasTable[prefix];
}
return {
number: num,
prefix: prefix,
unit: unit
};
};
if (typeof module !== 'undefined' && module.exports) {
module.exports = SI;
} else {
window.SI = SI;
}
})();