js 判断字符串中是否包含某个字符串的实现代码

var string = "foo",
    substring = "oo";
string.indexOf(substring) !== -1;//true

function instr(str, find) {
    if (str.indexOf(find) != -1) {
        return 1;
    } else {
        return 0;
    }
}

let searchVal = 'yyds'
let searchResult = searchVal.lastIndexOf('y')
console.log(searchResult) // 1

if (!String.prototype.includes) {
  String.prototype.includes = function(search, start) {
    'use strict';
    if (typeof start !== 'number') {
      start = 0;
    }

    if (start + search.length > this.length) {
      return false;
    } else {
      return this.indexOf(search, start) !== -1;
    }
  };
}

var str = 'To be, or not to be, that is the question.';

console.log(str.includes('To be'));       // true
console.log(str.includes('question'));    // true
console.log(str.includes('nonexistent')); // false
console.log(str.includes('To be', 1));    // false
console.log(str.includes('TO BE'));       // false

var string = "foo";
        var substring1 = "oo";
        var substring2 = "oq";
        string.includes(substring1); //true
        string.includes(substring2); //false

 let searchVal = 'yyds'
 let searchResult = searchVal.includes('y', 1)
 console.log(searchResult) // true

var string = "foo",
    expr = /oo/;
string.search(expr);// 返回1

 let searchVal = 'yyds'
 let searchResult = searchVal.search('y')
 console.log(searchResult) // 0  

let text = "Mr. Blue has a blue house";
let position = text.search(/blue/i);

_.includes('foobar', 'ob'); 

// → true

var string = "foo",
    expr = /oo/;  // no quotes here
expr.test(string);//true

var string = "foo",
    expr = /oo/,
    expr2 = /oa/;
string.match(expr);//["oo", index: 1, input: "foo", groups: undefined]
string.match(expr2);//null