Checks if array starts with a prefix. :package: :smiley_cat: :running: :vhs: :moon: :scroll: :newspaper: :blue_book:

Similar: prefix, prefixes, hasPrefix. Similar: hasValue, hasPrefix, hasInfix, hasSuffix, hasSubsequence, hasPermutation, hasPath.

This is part of package extra-array.

array.hasPrefix(x, y, [fc], [fm]);
// x:  an array
// y:  prefix?
// fc: compare function (a, b)
// fm: map function (v, i, x)

const array = require("extra-array");

var x = [1, 2, 3, 4];
array.hasPrefix(x, [1, 2]);
// true

array.hasPrefix(x, [-1, -2]);
// false

array.hasPrefix(x, [-1, -2], (a, b) => Math.abs(a) - Math.abs(b));
// true

array.hasPrefix(x, [-1, -2], null, v => Math.abs(v));
// true

References

• Data.List.isPrefixOf: Haskell
• List-Extra.isPrefixOf: elm
• String.prototype.startsWith: MDN web docs
• iterable-starts-with: @oprogramador