[Javascript][轉] How to format a Date in MM/dd/yyyy HH:mm:ss format in JavaScript?－碎碎念

重點：通常數值是個位數的話，前面會要補0，補0的話要先寫一個補0的function

Number.prototype.padLeft = function(base,chr){
    var  len = (String(base || 10).length - String(this).length)+1;
    return len > 0? new Array(len).join(chr || '0')+this : this;
}

Try something like this

var d = new Date,
    dformat = [d.getMonth()+1,
               d.getDate(),
               d.getFullYear()].join('/')+' '+
              [d.getHours(),
               d.getMinutes(),
               d.getSeconds()].join(':');

If you want leading zero's for values < 10, use this number extension

Number.prototype.padLeft = function(base,chr){
    var  len = (String(base || 10).length - String(this).length)+1;
    return len > 0? new Array(len).join(chr || '0')+this : this;
}
// usage
//=> 3..padLeft() => '03'
//=> 3..padLeft(100,'-') => '--3'

Applied to the previous code:

var d = new Date,
    dformat = [(d.getMonth()+1).padLeft(),
               d.getDate().padLeft(),
               d.getFullYear()].join('/') +' ' +
              [d.getHours().padLeft(),
               d.getMinutes().padLeft(),
               d.getSeconds().padLeft()].join(':');
//=> dformat => '05/17/2012 10:52:21'

See this code in jsfiddle

[edit 2019] Using ES20xx, you can use a template literal and the new padStart string extension.

var dt = new Date();

console.log(`${
    (dt.getMonth()+1).toString().padStart(2, '0')}/${
    dt.getDate().toString().padStart(2, '0')}/${
    dt.getFullYear().toString().padStart(4, '0')} ${
    dt.getHours().toString().padStart(2, '0')}:${
    dt.getMinutes().toString().padStart(2, '0')}:${
    dt.getSeconds().toString().padStart(2, '0')}`
);