Replace military time to normal time with Javascript

Question

With this script

getFormattedTime = function (fourDigitTime){
var hours24 = parseInt(fourDigitTime.substring(0,2));
var hours = ((hours24 + 11) % 12) + 1;
va         


        

Answer 1

Use this:

var getFormattedTime = function (fourDigitTime){
    var hours24 = parseInt(fourDigitTime.substring(0,2), 10);
    var hours = ((hours24 + 11) % 12) + 1;
    var amPm = hours24 > 11 ? 'pm' : 'am';
    var minutes = fourDigitTime.substring(2);

    return hours + ':' + minutes + amPm;
};

s = "Class starts at 1700, please be there by 1630 and sign in by 1645.";

c = s.replace(/([^\d]*)([0-9]{4})([^\d]*)/g, function(match, p1, p2, p3) {
    return p1 + getFormattedTime(p2) + p3
});

console.log(c);

Output:

Class starts at 5:00pm, please be there by 4:30pm and sign in by 4:45pm. 

Update

In your case:

s = $("body").html();

c = s.replace(/([^\d]*)([0-9]{4})([^\d]*)/g, function(match, p1, p2, p3) {
    return p1 + getFormattedTime(p2) + p3
});

$("body").html(c);

Update 2

If you have the time inside <td class="fourDigitTime">1500</td>, then use this:

$(".fourDigitTime").each(function() {
    $(this).text(getFormattedTime($(this).text());
});

Live Demo

Answer 2

You can use word boundaries in your regular expression to match 4 digits, and then your getFormattedTime function as a replacement function to .replace:

$('body').html(function(_, old) {
    return old.replace(/\b\d{4}\b/g, getFormattedTime);
});

Please notice also the comments by @Doorknob and @Pointy. To replace only time "numbers", you will need to markup them semantically, for example with html5 <time> tags:

Class starts at <time>1700</time>, please be there by <time>1630</time> and sign in by <time>1645</time>.

$('time').text(function(_, old) {
    return getFormattedTime(old);
});

Answer 3

Assuming the only digits displayed in the text are the times you can use:

var txt = 'Class starts at 0845, please be there by 1630 and sign in by 1645.'

getFormattedTime = function (fourDigitTime) {
    var hours24 = parseInt(fourDigitTime.substring(0, 2),10);
    var hours = ((hours24 + 11) % 12) + 1;
    var amPm = hours24 > 11 ? 'pm' : 'am';
    var minutes = fourDigitTime.substring(2);

    return hours + ':' + minutes + amPm;
};
/* replace numeric entities*/
var newTxt = txt.replace(/(\d+)/g, function (match) {
    return getFormattedTime(match)
})
$('body').html(newTxt);

DEMO : http://jsfiddle.net/q6HC9/1

EDIT: Wrapping times in a tag would greatly simplify situation. Wrap all military times in a span with a common class and then use the html() method

<span class="mil_time">0845</span>

getFormattedTime = function (fourDigitTime) {
    /* make sure add radix*/
    var hours24 = parseInt(fourDigitTime.substring(0, 2),10);
    var hours = ((hours24 + 11) % 12) + 1;
    var amPm = hours24 > 11 ? 'pm' : 'am';
    var minutes = fourDigitTime.substring(2);

    return hours + ':' + minutes + amPm;
};
/* find all spans and replace their content*/
$('span.mil_time').html(function( i, oldHtml){
   return getFormattedTime(oldHtml);
})