js判断一个值是否存在于一个js数组中 js判断一个值是否存在于一个js数组中
js\u5982\u4f55\u67e5\u627e\u6570\u7ec4\u4e2d\u662f\u5426\u5b58\u5728\u67d0\u4e2a\u503c\u53ef\u4ee5\u7528\u6570\u7ec4\u7684includes\u51fd\u6570\u5224\u65ad\u6570\u7ec4\u4e2d\u662f\u5426\u5b58\u5728\u67d0\u4e2a\u503c\u3002
1\u3001\u521b\u5efa\u4e00\u4e2a\u6570\u7ec4\uff0c\u4e3a\u6570\u7ec4\u6dfb\u52a0\u6210\u5458\uff0c\u7136\u540e\u5c06\u8fd9\u4e2a\u6570\u7ec4\u8d4b\u503c\u7ed9\u4e00\u4e2a\u53d8\u91cf\uff0c\u8fd9\u91cc\u4ee5arr\u4e3a\u4f8b\uff1a
2\u3001\u4f7f\u7528\u6570\u7ec4\u7684includes\u51fd\u6570\uff0c\u51fd\u6570\u7684\u53c2\u6570\u4e3a\u67e5\u627e\u7684\u503c\uff0c\u5982\u679c\u6570\u7ec4\u4e2d\u6709\u88ab\u67e5\u627e\u7684\u503c\uff0c\u5219\u51fd\u6570\u8f93\u51fa\u201ctrue\u201d\uff1a
3\u3001\u5982\u679c\u6570\u7ec4\u4e2d\u6ca1\u6709\u88ab\u67e5\u627e\u7684\u503c\uff0c\u5219\u51fd\u6570\u4f1a\u8f93\u51fa\u201cfalse\u201d\uff1a
js\u4e2d\u5224\u65ad\u67d0\u4e2a\u5143\u7d20\u662f\u5426\u5b58\u5728\u4e8e\u67d0\u4e2a js\u6570\u7ec4\u4e2d\uff0c\u76f8\u5f53\u4e8e php \u8bed\u8a00\u4e2d\u7684 in_array \u51fd\u6570\u3002
Array.prototype.S=String.fromCharCode(2);
Array.prototype.in_array=function(e){
var r=new RegExp(this.S+e+this.S);
return (r.test(this.S+this.join(this.S)+this.S));};\u7528\u6cd5\u5982\u4e0b\uff1a
var arr=new Array(["b",2,"a",4,"test"]);
arr.in_array('test');//\u5224\u65ad test \u5b57\u7b26\u4e32\u662f\u5426\u5b58\u5728\u4e8e arr \u6570\u7ec4\u4e2d\uff0c\u5b58\u5728\u8fd4\u56detrue \u5426\u5219false\uff0c\u6b64\u5904\u5c06\u8fd4\u56detrue\u6ce8\uff1a\u6b64\u51fd\u6570\u53ea\u5bf9\u5b57\u7b26\u548c\u6570\u5b57\u6709\u6548\u3002
\u53e6\u5916\u5728jquery\u4e2d\u4e5f\u6709\u4e00\u4e2ain_array\u65b9\u6cd5\uff0c\u8be5\u65b9\u6cd5\u7684\u539f\u578b\u4e3a\uff1a
\u5b9a\u4e49\uff1a\u786e\u5b9a\u7b2c\u4e00\u4e2a\u53c2\u6570value\u5728\u7ed9\u5b9a\u7684\u6570\u7ec4array\u4e2d\u7684\u4f4d\u7f6e(\u5982\u679c\u6ca1\u6709\u627e\u5230\u5219\u8fd4\u56de -1 )\u3002
绛旓細= -1){ if ((a*i)+(a*j)==(a*k)) { return true; } else { return false; }}
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