Javascript generates random numbers within a specified range

However, after a small effort, I finally touched the door and solved the problem.
Then, a formula is written, which should disappear. formula:
1. Starting from 1 to any value
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Parseint (math. Random () * Upper Limit + 1 );
2. From any value to any value
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Parseint (math. Random () * (upper limit-lower limit + 1) + lower limit );
The above formula uses parseint (), so we need to add 1; if we use math. Ceil (), we do not need to add 1. I am used to writing this...
Directory:
1. Demo 1 (directly generate a random number)
2. DEMO 2 (write as a function to generate a random number)
1. Demo 1 (directly generate a random number)
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<SCRIPT type = "text/JavaScript">
// <! [CDATA [
Window. onload = function (){
VaR n = Na = Nb = NC = '';
N = parseint (math. Random () * 10 + 1 );
NA = parseint (math. Random () * (20-11 + 1) + 11 );
NB = parseint (math. Random () * 100 + 1 );
NC = parseint (math. Random () * (100-51 + 1) + 51 );
VaR o = Document. getelementsbytagname ('input ');
O [0]. value = N;
O [1]. value = Na;
O [2]. value = Nb;
O [3]. value = NC;
} // Shawl. Qiu script
//]>
</SCRIPT>
1-10: <input type = "text"/> <br/>
11-20: <input type = "text"/> <br/>
1-100: <input type = "text"/> <br/>
51-100: <input type = "text"/> <br/>
2. DEMO 2 (write as a function to generate a random number)
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<SCRIPT type = "text/JavaScript">
// <! [CDATA [
Window. onload = function (){
VaR o = Document. getelementsbytagname ('input ');
O [0]. value = frandomby (10 );
O [1]. value = frandomby (11, 20 );
O [2]. value = frandomby (1,100 );
O [3]. value = frandomby (51,100 );
}
Function frandomby (under, over ){
Switch (arguments. Length ){
Case 1: Return parseint (math. Random () * under + 1 );
Case 2: Return parseint (math. Random () * (over-under + 1) + under );
Default: Return 0;
}
} // Shawl. Qiu script
//]>
</SCRIPT>
1-10: <input type = "text"/> <br/>
11-20: <input type = "text"/> <br/>
1-100: <input type = "text"/> <br/>
51-100: <input type = "text"/> <br/>