Highest and lowest possible result of this javascript expression?

Question

What is the highest number this javascript expression can evaluate to? What is the lowest number? Why?

+(''+Math.random()).substring(2)

Extra credit: How many different values can the expression evaluate to? Can it be every value from the minimum to the maximum, or are some intermediate values not obtainable due to rounding issues?

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Response to Daniel's answer (deleted, was 10000000000000000 max, 0 min):

I was playing around in Chrome's console and got this:

    Math.random();

>> 0.00012365682050585747

    '12365682050585747'.length

>> 17

    12365682050585747 > 10000000000000000

>> true

... so 10000000000000000 can't be the max!

Answer 1

For me the highest number is 1/0 (===Infinity) and the lowest obviously -1/0 (in Chromium browser).

Edit: You can also try parse a number from string to see which evaluates to Infinity.

var a = "1";
while(parseInt(a)!==Infinity) a=a+"0";
alert("Length of the highest number is: " + (a.length-1));

309 for me.