From 218934fa2ed1c702a6d3923d2aa2cc6b43c48684 Mon Sep 17 00:00:00 2001 From: Peter Bengtsson Date: Tue, 8 Dec 2020 14:43:23 -0500 Subject: initial commit --- .../global_objects/string/substring/index.html | 195 +++++++++++++++++++++ 1 file changed, 195 insertions(+) create mode 100644 files/vi/web/javascript/reference/global_objects/string/substring/index.html (limited to 'files/vi/web/javascript/reference/global_objects/string/substring') diff --git a/files/vi/web/javascript/reference/global_objects/string/substring/index.html b/files/vi/web/javascript/reference/global_objects/string/substring/index.html new file mode 100644 index 0000000000..e53b920581 --- /dev/null +++ b/files/vi/web/javascript/reference/global_objects/string/substring/index.html @@ -0,0 +1,195 @@ +--- +title: String.prototype.substring() +slug: Web/JavaScript/Reference/Global_Objects/String/substring +translation_of: Web/JavaScript/Reference/Global_Objects/String/substring +--- +
{{JSRef}}
+ +

substring() phương thức trả về chuỗi con của 1 chuỗi bắt đầu từ vị trí bắt đầu đến vị trí kết thúc, hoặc đến cuối chuỗi nếu không có vị trí kết thúc

+ +

Cú pháp

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str.substring(indexStart[, indexEnd])
+ +

Parameters

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+
indexStart
+
Một số integer giữa 0 và một số nhỏ hơn độ dài chuỗi, xác định vị trí kí tự đầu tiên trong chuỗi gốc để đưa vào chuỗi con.
+
indexEnd
+
Không bắt buộc. Một số integer giữa 0 và độ dài chuỗi. Chuỗi con không bao gồm ký tự ở vị trí indexEnd.
+
+ +

Return value

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Chuỗi con trả về là chuỗi nằm ở vị trí từ indexStart đến vị trí ( indexEnd - 1 )

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Description

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substring() lấy ký tự từ vị trí indexStart tới vị trí (nhưng không bao gồm) indexEnd. Đặc biệt:

+ + + +

Nếu indexStart lớn hơn indexEnd, chúng se được đổi chỗ; ví dụ, str.substring(1, 0) == str.substring(0, 1).

+ +

Examples

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Using substring()

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The following example uses substring() to display characters from the string 'Mozilla':

+ +
var anyString = 'Mozilla';
+
+// Displays 'Moz'
+console.log(anyString.substring(0, 3));
+console.log(anyString.substring(3, 0));
+
+// Displays 'lla'
+console.log(anyString.substring(4, 7));
+console.log(anyString.substring(4));
+console.log(anyString.substring(7, 4));
+
+// Displays 'Mozill'
+console.log(anyString.substring(0, 6));
+
+// Displays 'Mozilla'
+console.log(anyString.substring(0, 7));
+console.log(anyString.substring(0, 10));
+
+ +

Using substring() with length property

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The following example uses the substring() method and {{jsxref("String.length", "length")}} property to extract the last characters of a particular string. This method may be easier to remember, given that you don't need to know the starting and ending indices as you would in the above examples.

+ +
// Displays 'illa' the last 4 characters
+var anyString = 'Mozilla';
+var anyString4 = anyString.substring(anyString.length - 4);
+console.log(anyString4);
+
+// Displays 'zilla' the last 5 characters
+var anyString = 'Mozilla';
+var anyString5 = anyString.substring(anyString.length - 5);
+console.log(anyString5);
+
+ +

Replacing a substring within a string

+ +

The following example replaces a substring within a string. It will replace both individual characters and substrings. The function call at the end of the example changes the string 'Brave New World' into 'Brave New Web'.

+ +
// Replaces oldS with newS in the string fullS
+function replaceString(oldS, newS, fullS) {
+  for (var i = 0; i < fullS.length; ++i) {
+    if (fullS.substring(i, i + oldS.length) == oldS) {
+      fullS = fullS.substring(0, i) + newS + fullS.substring(i + oldS.length, fullS.length);
+    }
+  }
+  return fullS;
+}
+
+replaceString('World', 'Web', 'Brave New World');
+
+ +

Note that this can result in an infinite loop if oldS is itself a substring of newS — for example, if you attempted to replace 'World' with 'OtherWorld' here. A better method for replacing strings is as follows:

+ +
function replaceString(oldS, newS, fullS) {
+  return fullS.split(oldS).join(newS);
+}
+
+ +

The code above serves as an example for substring operations. If you need to replace substrings, most of the time you will want to use {{jsxref("String.prototype.replace()")}}.

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Specifications

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SpecificationStatusComment
{{SpecName('ES1')}}{{Spec2('ES1')}}Implemented in JavaScript 1.0.
{{SpecName('ES5.1', '#sec-15.5.4.15', 'String.prototype.substring')}}{{Spec2('ES5.1')}}
{{SpecName('ES6', '#sec-string.prototype.substring', 'String.prototype.substring')}}{{Spec2('ES6')}}
{{SpecName('ESDraft', '#sec-string.prototype.substring', 'String.prototype.substring')}}{{Spec2('ESDraft')}}
+ +

Browser compatibility

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{{CompatibilityTable}}
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FeatureChromeFirefox (Gecko)Internet ExplorerOperaSafari
Basic support{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}
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FeatureAndroidChrome for AndroidFirefox Mobile (Gecko)IE MobileOpera MobileSafari Mobile
Basic support{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}
+
+ +

See also

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