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e84f3bc Nov 1, 2018
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Array.prototype.delete(item [ , all [ , startOffset [ , endOffset ] ] ])

This removes the first occurrence of item from this (or all occurrences if all is truthy), optionally starting from startOffset, returning true if the item was found and false if it was not. This is mostly sugar for this, but the algorithm can be substantially optimized.

// Sugar for this
Array.prototype.delete = function (item, all = false, startOffset = undefined, endOffset = this.length) {
    let index = this.indexOf(item, startOffset)
    if (index < 0 || index >= endOffset) return false
    if (all) {
        do {
            this.splice(item, 1)
            index = this.indexOf(item, index)
        } while (index >= 0 && index < endOffset)
    } else {
        this.splice(item, 1)
    return true


It's pretty common to want to remove something from an array. And in some cases, an array is actually better than a set:

  • If it's almost always small and never contains strings (when the constant factor of hashing dominates)
  • If it's rarely tested or removed from, but frequently iterated.
  • If memory usage is a larger concern than computational complexity.

In this case, having it built-in allows a few other optimizations that aren't always possible, like using vector instructions for the whole thing when 1. the array is dense and 2. you don't need to dereference the array's elements to check them. There's also other language precedent: