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chad3814/gist:2924672

Last active August 29, 2024 05:43
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  1. chad3814 revised this gist Mar 10, 2021. 1 changed file with 5 additions and 5 deletions.
    10 changes: 5 additions & 5 deletions gistfile1.js
    View file
    Original file line number Diff line number Diff line change
    @@ -70,11 +70,11 @@ for (i = arr.length - 1; i >= 0; i -= 1) {
    }
    // arr is now: [5, 6, 9]

    / *
    * Another way is to augment the Array prototype to have a reject
    * function that is the opposite of the filter function (and add
    * the filter function if it doesn't exist)
    */
    /*
    * Another way is to augment the Array prototype to have a reject
    * function that is the opposite of the filter function (and add
    * the filter function if it doesn't exist)
    */
    if (!Array.prototype.filter) {
    // augment the Array prototype with a filter() that conforms
    // to ECMAScript5
  2. chad3814 revised this gist Jun 14, 2012. 1 changed file with 46 additions and 0 deletions.
    46 changes: 46 additions & 0 deletions gistfile1.js
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    Original file line number Diff line number Diff line change
    @@ -69,3 +69,49 @@ for (i = arr.length - 1; i >= 0; i -= 1) {
    }
    }
    // arr is now: [5, 6, 9]

    / *
    * Another way is to augment the Array prototype to have a reject
    * function that is the opposite of the filter function (and add
    * the filter function if it doesn't exist)
    */
    if (!Array.prototype.filter) {
    // augment the Array prototype with a filter() that conforms
    // to ECMAScript5
    // iterator - this function is called for each item, if it return
    // a truthy value, that item is added to the returned array
    // context - this is optional context to call the iterator. 'this'
    // inside the iterator will be set to context.
    // returns an array with only items for which the iterator returned
    // a truthy value
    Array.prototype.filter = function (iterator, context) {
    var arr = [];
    var i;
    for (i = 0; i < this.length; i += 1) {
    if (iterator.call(context, this[i])) {
    arr.push(this[i]);
    }
    }
    return arr;
    };
    }
    if (!Array.prototype.reject) {
    // augment the Array prototype with a reject() that is the opposite
    // of filter().
    // iterator - this function is called for each item, if it return
    // a truthy value, that item is not added to the returned array
    // context - this is optional context to call the iterator. 'this'
    // inside the iterator will be set to context.
    // returns an array with only items for which the iterator did not
    // return a truthy value
    Array.prototype.reject = function (iterator, context) {
    return this.filter(function (item) {
    return !iterator.call(context, item);
    });
    };
    }

    var arr = [5, 6, 7, 8, 9];
    arr = arr.reject(function (item) {
    return item === 7 || item === 8;
    });
  3. chad3814 revised this gist Jun 14, 2012. 1 changed file with 10 additions and 26 deletions.
    36 changes: 10 additions & 26 deletions gistfile1.js
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    Original file line number Diff line number Diff line change
    @@ -51,37 +51,21 @@ arr.forEach(function (item, index) {
    // arr is now something like: [5, 6, 8, 9]


    // DO use the third argument to the iterator function:
    // ALSO DON'T use the third argument to the iterator function thinking it's a clone:
    var arr = [5, 6, 7, 8, 9];
    arr.forEach(function (item, index, arr) {
    if (item === 7 || item === 8) {
    arr.splice(index, 1);
    }
    });
    // arr is now [5, 6, 9]
    /*
    * The 'arr' in the iterator is a clone of the original arr,
    * and at the end of the forEach, the original gets its length
    * and all elements set to the clone's length and elements.
    */

    // arr is now something like: [5, 6, 8, 9]

    // Of course not all browsers Array implement forEach so here's a monkey-patch:
    if (!Array.prototype.forEach) {
    // augment the Array prototype with a forEach that conforms
    // to ECMAScript5
    // iterator - a function with signature (item, index, array)
    // context - an optional context to call the iterator, 'this'
    // will be set to it inside of the iterator
    Array.prototype.forEach = function (iterator, context) {
    var arr = (new Array()).concat(this); // clone this
    var i;
    for(i = 0; i < this.length; i++) { // iterate over this, but use the clone
    iterator.call(context, arr[i], i, arr);
    }
    this.length = arr.length; // reset this to the clone's items
    for(i = 0; i < this.length; i++) {
    this[i] = arr[i];
    }
    };
    // DO use a reverse for-loop:
    var arr = [5, 6, 7, 8, 9];
    var i;
    for (i = arr.length - 1; i >= 0; i -= 1) {
    if (arr[i] === 7 || arr[i] === 8) {
    arr.splice(i, 1);
    }
    }
    // arr is now: [5, 6, 9]
  4. chad3814 revised this gist Jun 13, 2012. 1 changed file with 61 additions and 5 deletions.
    66 changes: 61 additions & 5 deletions gistfile1.js
    View file
    Original file line number Diff line number Diff line change
    @@ -1,16 +1,72 @@
    // If you want to splice in an iterator like Array's forEach() you can do it like this:
    // This is from my comment here: http://wolfram.kriesing.de/blog/index.php/2008/javascript-remove-element-from-array/comment-page-2#comment-466561

    /*
    * How to delete items from an Array in JavaScript, an exhaustive guide
    */

    // DON'T use the delete operator, it leaves a hole in the array:
    var arr = [4, 5, 6];
    arr.forEach(function (item, index, arr) {
    if (item === 5) {
    delete arr[1]; // arr now: [4, undefined, 6]

    // DO use splice:
    var arr = [4, 5, 6];
    arr.splice(1, 1);

    // If you want to find the item to delete you can use .indexOf()
    var arr = [4, 5, 6];
    var idx = arr.indexOf(5); // 1
    // be careful, .indexOf() will return -1 if the item is not found
    if (idx !== -1) {
    arr.splice(idx, 1);
    }

    // Not all browsers support .indexOf(), so here's a monkey-patch:
    if (!Array.prototype.indexOf) {
    // augment the Array prototype with an indexOf that conforms
    // to ECMAScript5
    // item - this is the object we're looking for
    // start - this is where to start looking
    // returns the index of the item if found, otherwise -1
    Array.prototype.indexOf = function (item, start) {
    start = start || 0;
    for( ; start < this.length; start++) {
    if (this[start] === item) {
    return start;
    }
    }
    return -1;
    };
    }



    // If you want to splice in an iterator like Array's forEach()
    // DON'T do this:
    var arr = [5, 6, 7, 8, 9];
    arr.forEach(function (item, index) {
    if (item === 7 || item === 8) {
    arr.splice(index, 1);
    }
    });
    // arr is now something like: [5, 6, 8, 9]


    // DO use the third argument to the iterator function:
    var arr = [5, 6, 7, 8, 9];
    arr.forEach(function (item, index, arr) {
    if (item === 7 || item === 8) {
    arr.splice(index, 1);
    }
    });
    // arr is now [5, 6, 9]
    /*
    The 'arr' in the lambda is a clone of the original arr, and at the end of the forEach, the original gets its length and all elements set to the clone's length and elements.
    * The 'arr' in the iterator is a clone of the original arr,
    * and at the end of the forEach, the original gets its length
    * and all elements set to the clone's length and elements.
    */

    // Of course not all browsers Array implement forEach so:

    // Of course not all browsers Array implement forEach so here's a monkey-patch:
    if (!Array.prototype.forEach) {
    // augment the Array prototype with a forEach that conforms
    // to ECMAScript5
  5. chad3814 created this gist Jun 13, 2012.
    31 changes: 31 additions & 0 deletions gistfile1.js
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,31 @@
    // If you want to splice in an iterator like Array's forEach() you can do it like this:
    var arr = [4, 5, 6];
    arr.forEach(function (item, index, arr) {
    if (item === 5) {
    arr.splice(index, 1);
    }
    });

    /*
    The 'arr' in the lambda is a clone of the original arr, and at the end of the forEach, the original gets its length and all elements set to the clone's length and elements.
    */

    // Of course not all browsers Array implement forEach so:
    if (!Array.prototype.forEach) {
    // augment the Array prototype with a forEach that conforms
    // to ECMAScript5
    // iterator - a function with signature (item, index, array)
    // context - an optional context to call the iterator, 'this'
    // will be set to it inside of the iterator
    Array.prototype.forEach = function (iterator, context) {
    var arr = (new Array()).concat(this); // clone this
    var i;
    for(i = 0; i < this.length; i++) { // iterate over this, but use the clone
    iterator.call(context, arr[i], i, arr);
    }
    this.length = arr.length; // reset this to the clone's items
    for(i = 0; i < this.length; i++) {
    this[i] = arr[i];
    }
    };
    }