switch-colon-spacing 
Spacing around colons improves readability of case/default clauses.
Rule Details 
This rule controls spacing around colons of case and default clauses in switch statements. This rule does the check only if the consecutive tokens exist on the same line.
This rule has 2 options that are boolean value.
json
{
    "switch-colon-spacing": ["error", {"after": true, "before": false}]
}- "after": true(Default) requires one or more spaces after colons.
- "after": falsedisallows spaces after colons.
- "before": truerequires one or more spaces before colons.
- "before": false(Default) disallows before colons.
Examples of incorrect code for this rule:
js
/*eslint @stylistic/js/switch-colon-spacing: "error"*/
switch (a) {
    case 0 :break;
    default :foo();
} incorrect 
Examples of correct code for this rule:
js
/*eslint @stylistic/js/switch-colon-spacing: "error"*/
switch (a) {
    case 0: foo(); break;
    case 1:
        bar();
        break;
    default:
        baz();
        break;
} correct 
Examples of incorrect code for this rule with {"after": false, "before": true} option:
js
/*eslint @stylistic/js/switch-colon-spacing: ["error", {"after": false, "before": true}]*/
switch (a) {
    case 0: break;
    default: foo();
} incorrect 
Examples of correct code for this rule with {"after": false, "before": true} option:
js
/*eslint @stylistic/js/switch-colon-spacing: ["error", {"after": false, "before": true}]*/
switch (a) {
    case 0 :foo(); break;
    case 1 :
        bar();
        break;
    default :
        baz();
        break;
} correct 
When Not To Use It 
If you don't want to notify spacing around colons of switch statements, then it's safe to disable this rule.