let teste = '123 mudar 40000000056';
let retorno = teste.split('').filter(item => Number(item)).join('');
console.log(retorno); // exclui os zeros
 
// deveria testar se é número
retorno = teste.split('').filter(item => ! isNaN(Number(item))).join('');
console.log(retorno); // só que ainda manteve os espaços, porque Number(' ') é zero
 
// então o certo é usar parseInt
retorno = teste.split('').filter(item => ! isNaN(parseInt(item))).join('');
console.log(retorno); // agora sim, só os números
 
 

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