/*
该方法实现将一个字符串achar中的某一个字符charA替换成指定的另外一个字符charB
*/
var replaceAll = function(achar,charA,charB){
     var rep = new RegExp(charA,"g");
     return achar.replace(rep,charB);
}

var achar ="人民城管爱人民";
var resChar = replaceAll(achar,"人","农");//农民城管爱农民

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