Query helpers

Import as import * as t from 'neotraverse'.

find · filter · some · every

t.find, t.filter, t.some, and t.every search over every node (root included). find/some stop at the first match; every stops at the first failure.

Example

import * as t from 'neotraverse';

const tree = { a: 1, b: { c: 2, d: 3 } };

t.find(tree, (ctx, x) => x === 2); // 2
t.filter(tree, (ctx) => ctx.isLeaf); // [1, 2, 3]
t.some(tree, (ctx, x) => x > 2); // true
t.every(tree, (ctx, x) => typeof x !== 'string'); // true

Example: collect leaf nodes

import * as t from 'neotraverse';

const leaves = t.filter({ a: [1, 2, 3], b: 4, d: { e: [7, 8], f: 9 } }, (ctx) => ctx.isLeaf);
// → [ 1, 2, 3, 4, 7, 8, 9 ]

reduce

t.reduce(obj, fn, init?, options?) folds over every node. See Core → reduce for seedless behaviour.

Example: sum numbers

import * as t from 'neotraverse';

const nested = { a: 1, b: { c: 2, d: 3 } };
const sum = t.reduce(nested, (_, acc, x) => (typeof x === 'number' ? acc + x : acc), 0);
// 6