Вот более понятный пример:
(Number(''.replace('1','').replace(',','')))
.toLocaleString('en-US', { style: 'currency', currency: 'USD' });
"$0.00"
(Number('1'.replace('$','').replace(',','')))
.toLocaleString('en-US', { style: 'currency', currency: 'USD' });
"$1.00"
(Number('10'.replace('$','').replace(',','')))
.toLocaleString('en-US', { style: 'currency', currency: 'USD' });
"$10.00"
(Number('100'.replace('$','').replace(',','')))
.toLocaleString('en-US', { style: 'currency', currency: 'USD' });
"$100.00"
(Number('1000'.replace('$','').replace(',','')))
.toLocaleString('en-US', { style: 'currency', currency: 'USD' });
"$1,000.00"
(Number('-1000'.replace('$','').replace(',','')))
.toLocaleString('en-US', { style: 'currency', currency: 'USD' });
"-$1,000.00"
(Number('-1000.09'.replace('$','').replace(',','')))
.toLocaleString('en-US', { style: 'currency', currency: 'USD' });
"-$1,000.09"
(Number('$-1,000.09'.replace('$','').replace(',','')))
.toLocaleString('en-US', { style: 'currency', currency: 'USD' });
"-$1,000.09"
(Number('-$1,000.09'.replace('$','').replace(',','')))
.toLocaleString('en-US', { style: 'currency', currency: 'USD' });
"-$1,000.09"