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case4/functions.js

/* New Perspectives on HTML, XHTML, and DHTML, 4th Edition Tutorial 14 Case Problem 4 Filename: functions.js Functions List: todayTxt() Displays the current date in the format mm/dd/yyyy. addCommas(value) Adds comma grouping to a numeric value (###,###,###.###). Returns a text string dollars(value) Converts a numeric value to a current format, including commas and the leading "$" symbol. Returns a text string. luhn(num) Returns a Boolean value indicating whether the number in the num text string fulfills the Luhn Formula. */ function todayTxt() { var Today=new Date(); return Today.getMonth()+1+"-"+Today.getDate()+"-"+Today.getFullYear(); } function addCommas(value) { valuetxt=value+""; decimals=""; re = /(-?\d+)(\d{3})/; decimalpos = valuetxt.search(/\./); if (decimalpos != -1) { decimals = "."+valuetxt.substring(decimalpos+1,valuetxt.length); valuetxt = valuetxt.substring(0,decimalpos); } while(re.test(valuetxt)) {valuetxt = valuetxt.replace(re,"$1,$2")} return valuetxt+=decimals; } function dollars(value) { n = Math.round(value*100)/100; if (n == Math.round(n)) {valuetxt=n+".00"} else if (n*10 == Math.round(n*10)) {valuetxt=n+"0"} else valuetxt=n+""; re = /(-?\d+)(\d{3})/; decimalpos = valuetxt.search(/\./); if (decimalpos != -1) { decimals = "."+valuetxt.substring(decimalpos+1,valuetxt.length); valuetxt = valuetxt.substring(0,decimalpos); } while(re.test(valuetxt)) {valuetxt = valuetxt.replace(re,"$1,$2")} return "$"+valuetxt+decimals; } function luhn(num) { var luhnTotal=0; for (i=num.length-1; i>=0; i--) { luhnTotal += parseInt(num.charAt(i)); i--; num2 = new String(num.charAt(i)*2); for (j=0; j < num2.length; j++) { luhnTotal += parseInt(num2.charAt(j)); } } return (luhnTotal % 10 == 0); }