Date.now is not supported in IE

[Aymkdn]

This little fix permits to make xlsx.js work with IE8

[tbenbrahim]

You would need more than that to support even IE10 running in compatiblity mode (IE7!) This is what I ended up using, in a separate file, ecma5-compat.js:

if (!Date.prototype.toISOString) {

    (function() {

        function pad(number) {
            var r = String(number);
            if (r.length === 1) {
                r = '0' + r;
            }
            return r;
        }

        Date.prototype.toISOString = function() {
            return this.getUTCFullYear()
                    + '-'
                    + pad(this.getUTCMonth() + 1)
                    + '-'
                    + pad(this.getUTCDate())
                    + 'T'
                    + pad(this.getUTCHours())
                    + ':'
                    + pad(this.getUTCMinutes())
                    + ':'
                    + pad(this.getUTCSeconds())
                    + '.'
                    + String((this.getUTCMilliseconds() / 1000).toFixed(3))
                            .slice(2, 5) + 'Z';
        };

    }());
}
if (!Date.now) {
    Date.now = function() {
        return new Date().valueOf();
    }
}

if (!Array.prototype.indexOf) {
    Array.prototype.indexOf = function(searchElement /* , fromIndex */) {
        'use strict';
        if (this == null) {
            throw new TypeError();
        }
        var n, k, t = Object(this), len = t.length >>> 0;

        if (len === 0) {
            return -1;
        }
        n = 0;
        if (arguments.length > 1) {
            n = Number(arguments[1]);
            if (n != n) { // shortcut for verifying if it's NaN
                n = 0;
            } else if (n != 0 && n != Infinity && n != -Infinity) {
                n = (n > 0 || -1) * Math.floor(Math.abs(n));
            }
        }
        if (n >= len) {
            return -1;
        }
        for (k = n >= 0 ? n : Math.max(len - Math.abs(n), 0); k < len; k++) {
            if (k in t && t[k] === searchElement) {
                return k;
            }
        }
        return -1;
    };
}
if (!window.JSON){
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}