Executing Java functionalities within JavaScript

Question

Executing Java functionalities within JavaScript

Differences in results between Java and Javascript can be observed when working with large integers.

For example:

getCode(1747,1763,-268087281,348400)

in Java returns 1921968083, while in Javascript it returns 2.510115715670451e+22.

Is there a way to achieve the Java result in Javascript?

After conducting some research, it appears that the issue may be related to signed/unsigned 32/64 bit integer operations. Adding |0 at the end of all operations got me closer with 1921618368, although not identical.

Java:

public String getCode(int intVal1, int intVal2, int intVal3, int IntA) {
    int intVal5 = intVal2 ^ intVal3  ;
    intVal5 = intVal5 + (intVal1 | IntA )  ;
    intVal5 = intVal5 * (intVal1 | intVal3  ) ;
    intVal5 = intVal5 * (intVal2 ^ IntA )  ;
    return String.valueOf(intVal5);
}

Javascript:

function getCode(intVal1,intVal2,intVal3,IntA)  {
    var intVal5 = intVal2 ^ intVal3  ;
    intVal5 = intVal5 + (intVal1 | IntA )  ;
    intVal5 = intVal5 * (intVal1 | intVal3  ) ;
    intVal5 = intVal5 * (intVal2 ^ IntA )  ;
    return intVal5;
}

java javascript porting

Answer 1

Answer №1

Using the |0 trick is effective for most operations in JavaScript when trying to mimic 32-bit integers, but it falls short when it comes to multiplication. The reason being that multiplying two large integers may yield a result that surpasses JavaScript's native double type precision. Consequently, when this is converted back to an integer, the value may be slightly inaccurate.

To address this limitation, Math.imul was introduced for genuine integer multiplication. Although relatively new, this method lacks support in older browsers such as IE. However, the linked page provides an alternative function that emulates imul for backward compatibility by separately multiplying the upper and lower halves of the numbers.

Below is a revised version of your function that utilizes |0 after addition and Math.imul for multiplication:

function getCode(intVal1, intVal2, intVal3, IntA) {
    var intVal5 = intVal2 ^ intVal3;
    intVal5 = intVal5 + (intVal1 | IntA) | 0;
    intVal5 = Math.imul(intVal5, (intVal1 | intVal3));
    intVal5 = Math.imul(intVal5, (intVal2 ^ IntA));
    return intVal5;
}
alert(getCode(1747, 1763, -268087281, 348400));

The result will be 1921968083, which matches the outcome in Java.

Answer 2

Using the |0 trick is effective for most operations in JavaScript when trying to mimic 32-bit integers, but it falls short when it comes to multiplication. The reason being that multiplying two large integers may yield a result that surpasses JavaScript's native double type precision. Consequently, when this is converted back to an integer, the value may be slightly inaccurate.

To address this limitation, Math.imul was introduced for genuine integer multiplication. Although relatively new, this method lacks support in older browsers such as IE. However, the linked page provides an alternative function that emulates imul for backward compatibility by separately multiplying the upper and lower halves of the numbers.

Below is a revised version of your function that utilizes |0 after addition and Math.imul for multiplication:

function getCode(intVal1, intVal2, intVal3, IntA) {
    var intVal5 = intVal2 ^ intVal3;
    intVal5 = intVal5 + (intVal1 | IntA) | 0;
    intVal5 = Math.imul(intVal5, (intVal1 | intVal3));
    intVal5 = Math.imul(intVal5, (intVal2 ^ IntA));
    return intVal5;
}
alert(getCode(1747, 1763, -268087281, 348400));

The result will be 1921968083, which matches the outcome in Java.

Executing Java functionalities within JavaScript

Answer №1

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