Fixing the Jump target cannot cross function boundary in Javascript

DanielNovember 8, 2023November 21, 2023

While working on some js code that contained named labels and break statements I ended up with the following error:

Jump target cannot cross function boundary

The code that I was trying to run was something similar to the one below:

const cars = ['Audi', 'BMW', 'Honda', 'Ford', 'Doge']

// ⛔️ using break in forEach with cause the
// "Jump target cannot cross function boundary" error
cars.forEach(carName => {
    console.log(carName)
    if(carName === 'BMW') {
        break
    }
})

The reason why this happened is because array forEach() is a function, and it seems that you can't use break to exit a function:

// ⛔️ this will also cause the  
// "Jump target cannot cross function boundary" error
function myFunc(x) {
    if(x === true) {
        break
    }
}

A quick fix for this can be to use a for ... of, or just a plain old for statement:

// 👍 Solution: use the return statement
for(let carName of cars) {
    console.log(carName)
    if(carName === 'BMW') {
        break
    }
}

The full code is on my Github and the running example is here.