How to determine whether there is a certain string in a string in es6

Judgment method: 1. Use includes(), the syntax "str.includes(searchString[, position])"; 2. Use indexOf(), the syntax "str.indexOf(substring)", if it returns " -1" is not available; 3. Use test(), match() or search() with regular expression search, syntax "exp.test(str)", "str.match(exp)".

The operating environment of this tutorial: Windows 7 system, ECMAScript version 6, Dell G3 computer.

es6 Method to determine whether a string contains a substring

Method 1: Use the includes() function

ES6 strings have a new includes method, which we can use to determine whether it contains substrings.

str.includes(searchString[, position])

• searchString: query substring

• position: optional, the position to start searching, the default is 0

'Blue Whale'.includes('Blue'); // returns true 'Blue Whale'.includes('blue'); // returns false

It should be noted that the includes method is case-sensitive.

For browsers that do not support es6, you can add es6-shim, such as:

require('es6-shim')

Method 2: Use the indexOf() function

indexOf This is a method we commonly use to determine whether it contains a substring. If a substring is contained, returns the index of the substring, otherwise returns -1.

var string = "foo", substring = "oo"; if(string.indexOf(substring) == -1) { console.log("不包含子字符串") } else { console.log("包含子字符串") }

Method 3: Using regular expressions

There are three ways to use regular expressions: test, match, search

1, test

var string = "foo", exp = /oo/; var result = exp.test(string);

test returns a Boolean value. Returns true if exists, false otherwise.

Note that the test function caller is a regular expression.

2, match

var string = "foo", exp = /oo/; var result = string.match(exp); console.log(result);

Output result:

["oo", index: 1, input: "foo"]

The caller is a string, if matched, an array is returned, including the matched content: regular expression, index and input.

3. search

var string = "foo", exp = /oo/; var result = string.search(exp);

returns the index of the searched substring. If the search cannot be performed, -1 will be returned

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