Avoid unnecessary jump statements

Docs > コード分析 > Static Analysis Rules > Avoid unnecessary jump statements

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Metadata

ID: javascript-best-practices/no-useless-jumps

Language: JavaScript

Severity: Notice

Category: Best Practices

Description

Jump statements like return, break, and continue are used to control the flow of the program, and while they can be extremely useful, unnecessary use of these statements can lead to code that is harder to read and understand.

This rule is important because unnecessary jump statements can clutter your code, make it less readable, and potentially introduce bugs. To adhere to this rule, you should only use jump statements where they are absolutely necessary. For instance, a return statement should only be used when you want to exit a function and return a value, a break statement should only be used to exit a loop or a switch statement, and a continue statement should only be used to skip the current iteration of a loop.

Non-Compliant Code Examples

function badReturn() {
    doComputation();
    // Unnecessary
    return;
}

function badLoops() {
    const arr = [1, 2, 3];
    for (const elem of arr) {
        console.log(elem);
        // Unnecessary
        continue;
    }

    while (true) {
        console.log(`1: ${arr[0]}`)
        console.log(`2: ${arr[1]}`)
        console.log(`3: ${arr[2]}`)
        break;
    }
}

Compliant Code Examples

function goodReturn() {
    doComputation();
    return 2;
}

function inSwitch() {
    const val = goodReturn();
    switch (val) {
        case 1:
            return;
        case 2:
            return;
        default:
            break;
    }
    doComputation();
}

function goodLoops() {
    const arr = [1, 2, 3, 4, 5];
    for (int = 0; i < arr.length, i++) {
        console.log(arr[i]);
        if (i === 2) {
            break;
        }
    }

    int i = 0;
    while (true) {
        console.log(`${i+1}: ${arr[i]}`);
        i++;
        if (i === 3) {
            break;
        }
    }
}