JavaScript函数的全局变量

Question

The problem is, that my function doesnt return the correct value. I think the reason is, because the callback is loaded after the value is returned.

The code:

function hexToBase58(inputNumber) { 
    var output = "";
    $.getScript("JavaScript/biginteger.js", function(){
        //hexToDecimal
        var sum = new BigInteger();
        for (var i = 0;i<inputNumber.length;i++)
        {
            sum = sum.multiply(new BigInteger(16)).add(new BigInteger(hexToDecimalChar(inputNumber.charAt(i))));    
        }

        //decimalToBase58
        var rest = new Array();
        var base = new BigInteger(58);
        var i = 0;          
        do
        {       
            rest[i] = sum.remainder(base).valueOf();
            sum = sum.divide(base);
            i++;
        }while(sum.valueOf() > 0)
        for(var j=0;j<i;j++)
        {
            output = output + decimalToBase58Char(rest[i-j-1]);
        }   
        console.log(output);    
    }); 
    console.log(output);
    return output;
}

I get two outputs:

• ""
• "5KAvT6dYsRsGdZKQoh2tCLvoFanZhXcGZUwqNs3RtcsWMojkSnA"

"output" is a global variable but the function does not return the second string but the first one. I dont know how to return the value from the inner function to the outer one.

It is very late and I tried a lot. I think maybe ajax can help. But I have no experience with ajax.

Answer 1

Don't load the script using $.getScript , but simply with a <script> tag.

<script src="JavaScript/biginteger.js"></script>

Then your function can be without the get script part:

function hexToBase58(inputNumber) { 
    var output = "";
    //hexToDecimal
    var sum = new BigInteger();
    for (var i = 0;i<inputNumber.length;i++)
    {
        sum = sum.multiply(new BigInteger(16)).add(
            new BigInteger(hexToDecimalChar(inputNumber.charAt(i))));    
    }

    //decimalToBase58
    var rest = new Array();
    var base = new BigInteger(58);
    var i = 0;          
    do
    {       
        rest[i] = sum.remainder(base).valueOf();
        sum = sum.divide(base);
        i++;
    }while(sum.valueOf() > 0)
    for(var j=0;j<i;j++)
    {
        output = output + decimalToBase58Char(rest[i-j-1]);
    }
    return output;
}