Date.prototype.valueOf()

The valueOf() method returns the primitive value of a Date object.

dateObj.valueOf()

The number of milliseconds between 1 January 1970 00:00:00 UTC and the given date.

The valueOf() method returns the primitive value of a Date object as a number data type, the number of milliseconds since midnight 01 January, 1970 UTC.

This method is functionally equivalent to the Date.prototype.getTime() method.

This method is usually called internally by JavaScript and not explicitly in code.

var x = new Date(56, 6, 17);
var myVar = x.valueOf();      // assigns -424713600000 to myVar

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• Object.prototype.valueOf()
• Date.prototype.getTime()