one-var-declaration-per-line 
Some developers declare multiple var statements on the same line:
js
var foo, bar, baz;Others prefer to declare one var per line.
js
var foo,
    bar,
    baz;Keeping to one of these styles across a project's codebase can help with maintaining code consistency.
Rule Details 
This rule enforces a consistent newlines around variable declarations. This rule ignores variable declarations inside for loop conditionals.
Options 
This rule has a single string option:
- "initializations"(default) enforces a newline around variable initializations
- "always"enforces a newline around variable declarations
initializations 
Examples of incorrect code for this rule with the default "initializations" option:
js
/* eslint @stylistic/one-var-declaration-per-line: ["error", "initializations"] */
var a, b, c = 0;
let d,
    e = 0, f; incorrect 
Examples of correct code for this rule with the default "initializations" option:
js
/* eslint @stylistic/one-var-declaration-per-line: ["error", "initializations"] */
var a, b;
let c,
    d;
let e,
    f = 0; correct 
always 
Examples of incorrect code for this rule with the "always" option:
js
/* eslint @stylistic/one-var-declaration-per-line: ["error", "always"] */
var a, b;
let c, d = 0;
const e = 0, f = 0; incorrect 
Examples of correct code for this rule with the "always" option:
js
/* eslint @stylistic/one-var-declaration-per-line: ["error", "always"] */
var a,
    b;
let c,
    d = 0; correct