A hyphen-separated United States phone number can be validated in JavaScript using the following regular expression:
(/^[2-9]\d{2}-\d{3}-\d{4}$/.test('222-333-4444');
Broken down into sections:
^[2-9] The phone number string must begin (^) with a digit between 2 and 9. This is the start of the area code. An area code cannot begin with 0 or 1.
\d{2} The first digit of [...]
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The JavaScript pop method can be used to remove elements from a JavaScript array.
//Removes 4 from the array
var aryTest = [1,2,3,4];
aryTest.pop();
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The JavaScript push method can be used to add elements to an array. Any values provided to the push function are appended to the end of the array.
//Adds 5 at the end of the array
var aryTest = [1,2,3,4];
aryTest.push(5);
document.write(aryTest);
Related Articles:
JavaScript unshift Method – Adding to an Array Beginning
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The number of elements in a JavaScript array can be retrieved by using the length property of the Array object. Note that this includes any undefined elements.
//Returns 4
var aryTest = [1,2,3,4];
document.write(aryTest.length);
If an element is then added at the 5th position of the array (JavaScript arrays are seeded at 0) the length of the array is [...]
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An array can be created in JavaScript by any of the following:
var aryTest = new Array();
This initializes an empty array
var aryTest = new Array(2);
This initializes an array with the number of elements indicated in the parenthesis. Each element is undefined, which is demonstrated by looping over the array as follows:
for(i=0;i<aryTest.length;i++)
alert(aryTest[i]);
var aryTest = new Array(1,2,3,4);
This initializes [...]
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A 5-digit United States Zip Code can be validated in JavaScript with a regular expression:
/^\d{5}$/.test('84601')
This specifies that the string being tested must begin and end as a digit with a length of five.
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Email addresses can be validated in JavaScript by using a regular expression:
(The following regular expression is actually one line – I have broken it into two so that it will wrap properly in WordPress.)
/^[A-Za-z0-9]+\w*([._-][a-zA-Z0-9]+)*@[A-Za-z0-9]+([._-][a-zA-Z0-9]+)*
\.[a-zA-Z]{2,}$/.test('joey@joey.com') ;
The JavaScript email address validation demonstrated here is somewhat loose to allow for varying email possibilities.
Broken down into sections:
^[A-Za-z0-9]+ – Begin [...]
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In JavaScript Regular Expressions the caret (^) can be used in square brackets as a negation character.
/[^abc]/ – would match for any characters that are not a, b or c.
/[^hb]at/ – would match for cat but not for hat or bat.
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In JavaScript, undefined means a variable has been declared but has not yet been assigned a value, such as:
var TestVar;
alert(TestVar); //shows undefined
alert(typeof TestVar); //shows undefined
null is an assignment value. It can be assigned to a variable as a representation of no value:
var TestVar = null;
alert(TestVar); //shows null
alert(typeof TestVar); //shows object
From the preceding examples, it [...]
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To specify an “OR” condition in JavaScript regular expressions, use the pipe character – |.
var StringToTest = “abc”;
var IsFound = /a|b/.test(StringToTest);
alert(IsFound);
The above statement returns true if ‘a’ or ‘b’ is in the test string.
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