如何使Array.indexOf()不区分大小写?

时间:2014-07-12 23:54:51

标签: javascript

我正在为一个网站制作一段代码,该网站将在数组中包含一个名称列表,并选择一个随机名称,我想添加一个功能,让用户添加或删除数组中的名称。我拥有所有这些功能,但在删除名称时,用户必须键入名称以匹配数组中的Case。我试图这样做就是Case-Insensitive,我做错了什么?

<html>
<!--Other code uneeded for this question-->
<p id="canidates"></p>
<body>
<input type="text" id="delname" /><button onclick="delName()">Remove Name from List</button>
<script>

//Array of names

var names = [];

//Other code uneeded for this question

//List of Canidates
document.getElementById('canidates').innerHTML = 
"<strong>List of Canidates:</strong> " + names.join(" | ");

//Other code uneeded for this question

//Remove name from Array

function delName() {
    var dnameVal = document.getElementById('delname').value;
    var pos = names.indexOf(dnameVal);
    var namepos = names[pos]
    var posstr = namepos.toUpperCase();
    var dup = dnameVal.toUpperCase();
    if(dup != posstr) {
        alert("Not a valid name");
        }
    else {
        names.splice(pos, 1);
        document.getElementById('canidates').innerHTML = 
        "<strong>List of Canidates:</strong> " + names.join(" | ");
        }
    }   
</script>
</body>
</html>

12 个答案:

答案 0 :(得分:43)

ES2015 findIndex

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var array = ['I', 'hAve', 'theSe', 'ITEMs'],
    query = 'these',
    result = array.findIndex(item => query.toLowerCase() === item.toLowerCase());

console.log(result); // 2
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答案 1 :(得分:26)

在ECMA-262第5版中,您可以使用Array.prototype.some进行此操作。

var array = [ 'I', 'hAve', 'theSe', 'ITEMs' ];
var query = 'these'.toLowerCase();
var index = -1;
array.some(function(element, i) {
    if (query === element.toLowerCase()) {
        index = i;
        return true;
    }
});
// Result: index = 2

答案 2 :(得分:21)

简单的方法是拥有一个包含所有大写字母的临时数组。然后您可以比较用户输入。所以你的代码可能变成这样的东西:

function delName() {
    var dnameVal = document.getElementById('delname').value;
    var upperCaseNames = names.map(function(value) {
      return value.toUpperCase();
    });
    var pos = upperCaseNames.indexOf(dnameVal.toUpperCase());

    if(pos === -1) {
        alert("Not a valid name");
        }
    else {
        names.splice(pos, 1);
        document.getElementById('canidates').innerHTML = 
        "<strong>List of Canidates:</strong> " + names.join(" | ");
        }
    }

希望这有助于解决您的问题。

答案 3 :(得分:6)

最优雅的解决方案是首先将数组转换为字符串,然后进行不区分大小写的比较。例如:

var needle = "PearS"
var haystack = ["Apple", "banNnas", "pEArs"];
var stricmp = haystack.toString().toLowerCase(); // returns 
                                   // "apple,bananas,pears"
if (stricmp.indexOf(needle.toLowerCase()) > -1) {
    // the search term was found in the array
} else {
    // the search term was not found in the array
}

答案 4 :(得分:5)

可能最好创建自己的自定义indexOf方法,就像这样。

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'use strict';

var customIndexOf = function(arrayLike, searchElement) {
  var object = Object(arrayLike);
  var length = object.length >>> 0;
  var fromIndex = arguments.length > 2 ? arguments[2] >> 0 : 0;
  if (length < 1 || typeof searchElement !== 'string' || fromIndex >= length) {
    return -1;
  }

  if (fromIndex < 0) {
    fromIndex = Math.max(length - Math.abs(fromIndex), 0);
  }

  var search = searchElement.toLowerCase();
  for (var index = fromIndex; index < length; index += 1) {
    if (index in object) {
      var item = object[index];
      if (typeof item === 'string' && search === item.toLowerCase()) {
        return index;
      }
    }
  }

  return -1;
};

var names = [
  'John',
  'Anne',
  'Brian'
];

console.log(customIndexOf(names, 'aNnE'));
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甚至

&#13;
&#13;
'use strict';

var customIndexOf = function(array, searchElement, fromIndex) {
  return array.map(function(value) {
    return value.toLowerCase();
  }).indexOf(searchElement.toLowerCase(), fromIndex);
};

var names = [
  'John',
  'Anne',
  'Brian'
];

console.log(customIndexOf(names, 'aNnE'));
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您可能还想添加更多检查,以确保数组中的每个元素实际上都是String,并且searchElement实际上也是String。如果是ES5之前,则加载适当的shims

答案 5 :(得分:1)

可以通过map方法使用。例如,见下面的代码

var _name = ['prasho','abraham','sam','anna']
var _list = [{name:'prasho'},{name:'Gorge'}];

for(var i=0;i<_list.length;i++)
{
   if(_name.map(function (c) {
     return c.toLowerCase();
   }).indexOf(_list[i].name.toLowerCase()) != -1) { 
  //do what ever
   }else{
     //do what ever
   }
}

More info

答案 6 :(得分:1)

您可以使用Array.prototype.find()

found = myArray.find(key => key.toUpperCase() === searchString.toUpperCase()) != undefined;

示例:

myArray = ['An', 'aRRay', 'oF', 'StringS'];
searchString = 'array';
found = myArray.find(key => key.toUpperCase() === searchString.toUpperCase()) != undefined;
if (found ) {
    // The array contains the search string
}
else {
    // Search string not found
}

注意:数组不能包含undefined作为值。

答案 7 :(得分:0)

将数组转换为由分隔符分隔的字符串,将该字符串转换为小写,然后通过相同的分隔符将字符串拆分回数组:

function findIt(arr, find, del) {
  if (!del) { del = '_//_'; }
  arr = arr.join(del).toLowerCase().split(del);
  return arr.indexOf(find.toLowerCase());
}

var arr = ['Tom Riddle', 'Ron Weasley', 'Harry Potter', 'Hermione Granger'];
var find = 'HaRrY PoTtEr';
var index = findIt(arr, find);

if (~index) {
  alert('Found ' + arr[index] + '! :D');
} else {
  alert('Did not find it. D:');
}

答案 8 :(得分:0)

这是最短的一个。

haystack.join(' ').toLowerCase().split(' ').indexOf(needle.toLowerCase())

答案 9 :(得分:0)

我需要与此类似的东西,我需要使用includes比较两个字符串,并且需要能够支持不区分大小写的搜索,因此我编写了以下小函数

function compare(l1: string, l2: string, ignoreCase = true): boolean {
  return (ignoreCase ? l1.toLowerCase() : l1).includes((ignoreCase ? l2.toLowerCase() : l2));
}

相同的原则可能适用于indexOf,如下所示

function indexOf(l1: string, l2: string, ignoreCase = true): number {
  return (ignoreCase ? l1.toLowerCase() : l1).indexOf((ignoreCase ? l2.toLowerCase() : l2));
}

我知道这不是专门的Array.indexOf,但希望这对某人在旅行途中遇到此问题有所帮助。

不过,要回答ops问题,您可以将其类似地应用于与answer中与此@ULIT JAIDEE组合而成的数组(对此的微小变化是使用tilda字符作为分隔符,以防出现以下情况)数组值包含空格)

function compare(l1: any[], l2: any[], ignoreCase = true): boolean {
  return (ignoreCase ? l1.join('~').toLowerCase().split('~') : l1).indexOf((ignoreCase ? l2.join('~').toLowerCase().split('~') : l2));
}

再次希望这会有所帮助。

答案 10 :(得分:0)

// unique only, removes latter occurrences    
array.filter((v, i, a) => a.findIndex(j => v.toLowerCase() === j.toLowerCase()) === i);

答案 11 :(得分:-2)

你不能让它不区分大小写。我会使用一个对象来保存一组名称:

function Names() {
    this.names = {};

    this.getKey = function(name) {
        return name.toLowerCase();
    }

    this.add = function(name) {
        this.names[this.getKey(name)] = name;
    }

    this.remove = function(name) {
        var key = this.getKey(name);

        if (key in this.names) {
            delete this.names[key];
        } else {
            throw Error('Name does not exist');
        }
    }

    this.toString = function() {
        var names = [];

        for (var key in this.names) {
            names.push(this.names[key]);
        }

        return names.join(' | ');
    }
}

var names = new Names();

function update() {
    document.getElementById('canidates').innerHTML = '<strong>List of Canidates:</strong> ' + names;
}

function deleteName() {
    var name = document.getElementById('delname').value;

    try {
        names.remove(name);
        update();
    } catch {
        alert('Not a valid name');
    }
}

update();